By initial impressions rift is an amazing game and i doubt it will be a flop, infact i think that it will be quiet popular of a game. from present impression's the classes are getting there in the way of balance, but that's a long process, warcraft took nearly 4 years to start to truly balance classes.
Now to the good part, the wizards. Unlike warcraft, mage's aren't limited to a damage roll, infact mage's are able to become a supportive buff class and a healer class below you will find my view of each class;
The Elementalists are a pet class, they have a reliance on their summoned elemental to either tank or damage deal for them, this make's them a powerful opponent, though it is also their greatest weakness as with any pet class, loss of the pet is almost certain doom for the Elementalist during combat.
much alike, well every warlock in every game, the warlock of RIFT is a DOT class, though unlike warcraft it does not summon demons, the suffer the same strength (strong crippling debuffs) but have the same weakness (time is an essence to winning, if the enemy can hold you down your dead)
This is one of the more intriguing specs it's a legitimate healer, that heals via damage and via reflections. For those of you who came to wizardry from warcraft, in the days of DnD and several PC games based of the DnD series, wizard's where able to become healers. and following in DnD's tradition, healing wizard's are AWESOME!
Fire fire fire, now we couldn't have a magic game without it could we? pyromancers are much alike fire mages of the old, strong single target, noticeable but not amazing aoe, playing a pyromancer felt very similar to playing a fire mage in wow so not too much need to comment here :P
Similar to DK's of old, summon the dead, siphon life from others, unlike warlocks they are death damage not shadow damage, they work similar to Spriest's if i say so myself, with a more permanent shadow fiend. tend's to be our preferred leveling spec.
Shaman's anyone? Lightning and water magic, save for the 0 lvl ability shock i found this tree rather uninteresting.
more to come after i get a go at the rest of the classes :)