You should join! Rift is nowhere as much of a grind as Old FF MMO was and is much more polished/intuitive/user-friendly/supported than New FF MMO.
Some things specifically about what you have experience with...
It plays very similar to WoW in many ways but takes the good elements of many past MMOs to stand above the over-crowded genre.
If you thought WoWs leveling was too slow then you'll like Rift. If you just focus and rush, it won't take long to get to max level... however, there are many things to do along the way where you stop and smell the roses and don't need to blitz to level 50. Many people complain about leveling too fast and running out of things to do, but more content is coming consistently.
There are quite a few kinks, tweaks, and issues still being worked out with balancing and experimentation of content on the way, but Trion does a good job of communicating and refining to where after the first few months I think we will see a stabilizing product and many improvements.
Most of the forums are full of QQers, as they are with any MMO really, so take everything with a grain of salt (although this one seems to be a bit more relaxed and mature).
As far as class recommendations, its really to hard to express anything for someone else. I actually enjoy them all and have a serious case of "Altitus" with all the classes and both factions - the only downside to this is the starting areas are only faction based and not race/class based like they are in WoW so making your 3rd or 4th character can be a little repetitive. But there is such a difference in how each class is played and even the drastically different souls per calling that it doesn't really get old. In fact, that's one of the major things going for Rift. I'd recommend just playing with the soul trees here and see what sounds appealing to you. I'm sure you know by now but Rogues can DPS, Tank and a little heal (support), Mages can also heal, Clerics can do it all, and Warriors can tank, melee and RANGE dps (so its pretty dynamic and you can purchase additional roles!).
Enjoy (if you haven't started already, in which case you'll never read this because you'll be too busy playing!)
Edited, May 4th 2011 1:42pm by jocool32