Whenever you add a new race into an already established game, the question of game balance becomes an important issue. Rise of the Elves does an excellent job in this regard, as the Elf retinue is not overly powerful nor are they fodder for the other four races.
Perhaps the biggest plus is that these Elves aren't fey forest pansies like the usual Tolien-influenced woodland folk. They're as dark and pissed-off as everyone else in the Disciples world. [Mar 2004, p.71]
If you are a veteran of the D2 series, Rise of the Elves adds in a cool new army to play with and hours of gameplay for the new missions, and while theres nothing new or revolutionary that really seemed to go on, that can be a good thing.