There's quite a bit of buzz out there about Rift these days.
Some people I know in WoW have been seriously considering letting their subscription lapse in favor of Rift, and others are planning on playing both games concurrently. That a decent subset of the WoW community seems to be grumbling over the current state of WoW only heightens the call of Rift.
I can attest to the allure of the "shiny!" that Rift provides; I spent several days poking around the last open Beta and was impressed with what I found. The story seems very interesting, particularly the aspect of the Rifts themselves. Imagine the Elemental Invasion Cata event, but with the Elementals moving in and taking over world areas if you don't beat them back. Throw into this the faction conflicts of religion vs. technology and insiders vs. outsiders, and you've got a very entertaining backstory. Of course, the story starts out with the bleakest of outcomes, and your job is to prevent that disaster from occurring.
The concept of selecting three souls (talent trees) from a large pool of available souls is a customizer's dream, and a theorycrafter's nightmare. From what I've seen online, there are theorycrafters working on optimal builds for each class (naturally), but it may take a long time before things are hammered out. FWIW, I found the array of choices almost too much, and I can see where a noob would be overwhelmed.
As for the introductory quests, I found them straightforward enough. If you've done intro quests before, there's no real surprise here. What did surprise me was that once you got out into the regular game world, you're thrown to the wolves. Imagine an entire world where your low level areas are mixed with the high level ones --like Scarlet Monastery in Tirisfal Glades-- and you end up getting thwacked by high level NPCs before you knew what was happening. Well, that's what the Rift world is like. You don't mess around in this world, that's for certain.
What do I think of Rift?
Well, Rift is not a world for beginners. Although Trion does take pains to lead people along throughout the intro quest line, the overall player customization and world design implies that their target audience is the experienced MMO player who is dissatisfied with their current game. If you came into the game cold, you'd be lost.
Rift is also following the WoW model with raiding as endgame. For those who were hoping for more of a sandbox environment, this has to be disheartening. As for the non-raider, it gets a big /shrug out of me.
Rift also takes pains to level the playing field. There is no customization for the UI beyond what the game is currently capable of. All of those nifty third-party addons you have in WoW will have to hit the road. And from what I can tell, that's causing no small bit of angst in the message boards. Of course, I leveled Q to L80 with the original UI largely intact, so I don't think it that big a deal.
Will I switch to Rift? Not right now, no. I can only afford one pay-per-month MMO, and WoW is the one for me. Given that I'm still leveling my main and my two primary alts to L85, I haven't exhausted my interest in the game yet.* That said, I can see it's appeal. There's potentially a great story to work with, and an entirely new world worth exploring. I doubt Rift will be a WoW-killer --I suspect an MMO based on Bioware's Dragon Age would be that game-- but it will find a niche market. I wish Trion luck, and if Rift succeeds, so much the better.
*That's one small side bonus in taking it nice and slow in the leveling, there's no "is that all there is?" feeling with 4.1 hitting the PTR servers.)