I was never lucky/crazy enough to own a Neo Geo AES, so the King of Fighters series mainly existed in a parallel universe I didn't have access to, not until I started dabbling in MAME anyway. Even then, a lack of human opponents and a fearsome hardcore reputation ensured that my occasional forays into it were brief and baffling. It's no fun learning a fighter on your lonesome.
Fate intervened, and a friend steeped in KoF gave me a thorough introduction to the series, explaining characters, chunks of storyline, and most importantly playing techniques. A couple of marathon sessions on '98 and 2002 layed the groundwork, but the release of 2002UM early in the year sealed the deal.
Without passing myself off as someone who knows a great deal about the series - I certainly don't - I can say that 2002UM is basically the best version of KoF out there. Call it a greatest hits, a distillation of everything that works. It's another 'dream match' type of game, like '98. No storyline to speak of, just a whole bunch of characters spoiling for a fight (a mammoth roster ensures that everyone's favourites are accounted for).
To a pixel art fan, the AES-based KoF sprites and artwork still look great and move with enough fluidity to stand alongside their polygonal rivals, and the new splash art strikes a nice balance between classic SNK stylings and a more modern Anime look. I've found the character art to be very hit-and-miss from this series, with some truly scary years in there. With XI, XII and this instalment they seems to have finally hit a stride.
And the gameplay? As you might expect from a fighter that places above SFIV in this list, the action is responsive, crunchy, absolutely rock solid. One thing I really like about these games is the weight behind the hits and the physical feel of the characters on the screen. A lot of fighting game wannabes fail in delivering that very fundamental aspect.
Once again, the two-player arcade experience triumphs. It caters for a quick fix but it can also consume your entire day. It doesn't matter if it's not the most visually flashy kid on the block either, because - hoary cliché be damned - great gameplay is ageless.