As mentioned previously, all this ease and usability comes at the cost of a frustrating initial grind to break out of your early-game weakness. Disgaea will seem sadistically difficult during the first five hours or so; this may be off-putting to some players, but the rewards are well worth that initial time investment. The designers seem to have built the first part of the game with an eye toward letting players try the old-fashioned style just to learn how irritating it can be; once you get the chops to try Disgaea's unique ways of powering up, you'll know exactly why you should. This is not a game to be beaten in a quick sitting or even a weekend; there is easily a hundred hours' worth of battle here, every bit of it a blast to play.
Bottom line: Disgaea DS is a faithful translation of the PS2 original and well worth the cost for anyone looking for an outstanding SRPG on the go. This is one of the best DS games to come out this year.
Recommendation: Buy it. If you're already an SRPG fan this is more of the same; if you are not yet on board, this is the perfect introduction to the genre.