Ok, so I tried this out yesterday and I have to say, I'm pretty impressed. I've been playing WoW since vanilla and I really enjoy it but I would love to find an MMO that will pull me away. I'm not saying Rift is it, but from what I've seen so far, it could be the closest to make me want to leave WoW.
I really like the soul system, it gives each class so many options. Ever since Diablo 2, I've loved the necromancer class. To be honest, I wanted to try Rift in the first place because I read they have that class. While I only hit level 4, I like what I see from the class. I chose necromancer as my first soul and warlock as my second. Obviously I did not have access to very many spells, but I liked what I started out with.
The interface is almost exactly like WoW. I know some people will complain and call it a WoW ripoff but I could care less. If anything, I think it's beneficial. I pretty much know how everything works from playing WoW so it's a welcome theme to me.
The graphics are very nice, it's refreshing to play something with a more realistic look. While I love WoW's kind of cartoony look, more realism is a nice change.
The combat is the same as WoW, which again is fine by me. I was having a lot of fun with the few spells at my disposal.
Since Cataclysm is still new and I have a lot I can be doing in it, I won't dive in head first to Rift right away. But I will be watching it very closely. Unfortunately if I do start to play it, I'll most likely stop when Star Wars The Old Republic comes out, I'm looking VERY forward to that game.