Accessible isn't a four letter word.
DOA4 takes the tried and true formula of it's predecessors, tweaks it a little, and delivers a solid package to the 360 that any gamer could enjoy. Even though each character has a wealth of moves (75 or so on average) the majority of these are simple to perform, and more often than not share a button scheme with the moves of a dozen other characters. As a result, getting practice with one character can really improve your overall skill, rather than just your ability with that one character.
The only real downside to this title is the tweaking that has been done to counter system. In previous titles, just about any move could be countered with a button press. Many people felt this took a lot of the fun and challenge out of an otherwise excellent game, and Team Ninja decided to address these concerns. Unfortunately they've gone from one end of the difficulty spectrum to the other. Countering has become a mind-numbingly frustrating chore, so much so that you may find yourself spending hours practicing just to get comfortable enough with the new system to pull of a counter every now and then.
The online play offers a "Winner-Stays" scenario that does a fantastic job of recreating the arcade experience of the early-90's. The only downside to the online play is the inevitable lag that occurs at random. It can be really frustrating to deal with -- you can win 19 lag-free matches in a row and be annihilated in the 20th because you only see one out of a hundred frames.
On the bright side, DOA4 offers quite a robust single-player game, so if you want to avoid lag-related frustration you've got a decent alternative. Thanks to the 360's achievements system, DOA4's single-player has a ton of replayability. The game makes good use of the achievement system, offering a whopping 45 achievements that range in difficulty from ludicrously simple (beating story mode with one character) to the insanely difficult (100 wins in survival mode? not in this lifetime.) Some of these can only be attained by playing online though, so if you're looking for all 1000 gamerpoints you'll need to suffer through the lag issues. Overall, the achievements in this game are fairly well balanced. Any gamer willing to invest the time can easily walk away with 200-300 gamerpoints. Anything more than that will require some dedication, though. If you don't care about gamerpoints, not to worry, there's a lot here for you too. Everything from extra characters to extra costumes can be unlocked through regular play (and getting all of these will take you a long, long time.)
Overall, DOA4 is a fantastic package, offering tons of unlockables, accessible gameplay, and a refreshing (but laggy) online mode. A definite must-have for any fan of fighting games -- even the casual ones.