Play is Methodical
A game of Diplomacy develops slowly; every turn takes about twenty to thirty minutes (when playing face-to-face) or several days to weeks (when playing by post). Most of the pleasure of the game results from methodical contemplation and careful planning. Likewise, there is no chance in Diplomacy aside from the choices of the other players, which makes tactical planning a fascinating mental exercise of projecting moves and counter-moves. If a player enjoys games like chess, then Diplomacy could be worth trying.
There is another aspect to the methodical nature of Diplomacy that is not reflected in Chess: the amount of writing involved. When playing face-to-face or in some methods of post play, all orders must be written (in a particular format, no less), and when playing by post most correspondence will be mostly written (I have heard of some players coordination moves by phone or by meeting up, but that is less common than electronic or, for old-school players, paper messages). I have tried to introduce the game to some friends who have flat-out balked at the amount of writing involved. In this sense roleplaying games like Dungeons and Dragons which require careful maintenance of a character sheet (or entire worlds if one is the DM) are a better example of the type of necessary disposition.
If you find this difficult
Although there really isn’t a way to make Diplomacy a faster paced game, there are options and variants which can reduce the burden of these aspects. If you find writing out orders according to a stringently enforced syntax to be frustrating, one can try playing with electronic engines (through the web such as with playdiplomacy.com or on one’s computer using an engine like jDip) which allow more intuitive point-and-click interfaces for orders.
Additionally, a variant which might be of interest is one which is usually called ‘Gunboat Diplomacy’ or ‘No-press Diplomacy’ and disallows direct communication between players (although much can be communicated through orders, much like bidding in Bridge). The pace of a gunboat game tends to be faster than standard games due to the lack of a distinct Diplomacy phase, and therefore might be of more interest to those who finding composing messages and maintaining relationships burdensome.
Players Must Handle Losing
This is a difficult characteristic to find, particularly among methodical game players (who tend to like games, and therefore play a lot of games and get rather good at them). However, there is no getting around the fact that Diplomacy is difficult. There are seven people playing who generally would all like to win, and thus the game becomes a volatile mixture of competing interests. Even the best players will face stagnation or outright elimination in a large number of games they play.
Although there are other games that support a large number of players (for example, Settlers of Catan with its expansion can have six players), those games are able to mitigate the fact that only one of those players can win by having every player simultaneously advancing and accomplishing small goals in a steady progression toward victory. In Diplomacy, however, it is a very real possibility that one’s forces will be whittled down before one is eliminated from the game entirely.
If you find this difficult
I am going to combine this section with the response to the next section, as they are closely related.
Players Must Handle Being Stabbed
Closely related to being able to lose without getting too upset is the capacity to be stabbed in the back (obviously metaphorically). Everyone who plays games knows that losing happens, but what makes Diplomacy different is that almost all losses come at the hands of a coalition of other players, with one or more of those players professing friendship (or, at the very least, ambivalence) right up until the devastating moment of the strike. In a game like Settlers of Catan a trade boycott might be enacted against the strongest player, or a player might spitefully refuse to trade with a particular opponent, but players cannot connive to directly destroy one another.
Of course, I’m not saying that one must like getting stabbed, but it is important to recognize that it is not (or, at least, should not be) a personal vendetta that has led to one player promising one set of moves and instead making another. There are all sorts of moral codes and guidelines that various enthusiasts have developed over the years outlining when one should and should not go about putting the metaphorical knife in another player’s back, but I feel such an exercise is largely useless. The only point I think that everyone needs to be aware of at the outset of the game is that it is a game. When France promises to support England's convoy into Belgium with the French fleet sitting in the English Channel, but then instead sails into a now vacant London, England will obviously be miffed. The important thing is to make sure that any hurt or anger experienced is transient; if one finds oneself holding grudges well past the end of the game or against the other player as a person rather than as a Diplomacy player, then perhaps Diplomacy is not a game one should be playing. Not only will it be hard to have fun if you are always finding yourself nurturing ill-will toward other players, but spoiling friendships over a board game would be a terrible waste.
If you find this difficult
Richard Sharp makes the claim in his book The Game of Diplomacy that ‘good ally’ players (those who make alliances and doggedly stick with them through the entire game, come what may) are beginners much more often than experienced players (the other extreme is that new players try to be too diplomatically slippery and make a lot of very poor stabs). While I think he is unfairly hostile to the ‘good ally’ style of play (there is nothing inherently wrong with it, so long as the alliance itself is a spontaneous entity contained to the single game and not simply two players deciding to ally in every game regardless of what happens), I do not think he is wrong about the demographics of ‘good ally’ players. Richard Sharp does not make any attempt to address the reason for such a tendency, though, and I think that is something which is important to bring up. Handling being stabbed is a psychological skill, and it takes practice. Beginners are less likely to recognize the stab as a pragmatic maneuver on the part of their erstwhile allies, and are instead more likely to interpret it as a personal betrayal. This, in turn, also makes beginners less likely to execute stabs themselves, since they see it as a personal affront to another player whom they hold no actual ill will against.
Therefore, I think one manner of getting over a difficulty with the harsher diplomatic aspects of the game is to play a few more games, but treat the games as practice and consciously start the game with low expectations. A good way to do this is to play online with players you have never met. Take some risks and see what happens. See if you can predict when your allies will backstab you, as predicting a stab is the first step in preventing it. Keep in mind that these games are practice, and in that way keep yourself emotionally distant. Once this has been accomplished in a few practice games, you will realize that there is no great shame in losing or being stabbed in the back, and it should be easier to maintain that resilience in other games of Diplomacy.
Note: If you are going to read Richard Sharp's book that I have linked to, it is also a good idea to read this review. As the reviewer points out, Sharp writes well, but is exceedingly biased toward the central powers of Germany and Austria-Hungary, to the point of advocating play styles that are not necessarily in the best interests of the players involved. It can easily come about that France and England (or France and Russia, England and Russia, or even France, England, and Russia if Germany is particularly unlucky) might find it in their best interest to attack Germany early and hard, despite Sharp's view that France and England must immediately be at each other's throats and it is foolhardy for Russia to do anything but yield gracefully to the German Empire.