Well I'm lv15 now, i've clocked a good amount of gametime to get a feel for at least the basic game
The PVE experience is pretty much WoW + GW2 random events/hearts, so instead of just doing the classic WoW-style questing, GW2-style random events pop up around the map all the time, you can join the zerg and leech exp/gold from doing it. I gained 4 levels in 30 minutes by doing a thing called "Instant Adventure" which is a huge map-wide eventline, and joined up with like 20 other random people to zerg these quests around the map, it was awesome fun.
The class system is pretty diverse as well - 4 main classes (Warrior, Rogue, Cleric, Mage) - but instead of each class having only 3 specs (like in WoW), Rift offers you 9 spec per class (10 if you've bought the expansion pack), which gives you A LOAD OF different ways to play. You can have up to 3 specs activated at one time, or you can dump all your talent points into 1 spec or even split it between 2, it's totally up to you.
You can also start riding mounts at Lv10 so you get around much faster earlier than in WoW
I'll report more later once I try PVP and do some dungeons and stuff. So far I'm enjoying it and really dig it
**My toonname is Chibiwong. (on Seastone - Defiant), add me if you're on my server