Best MMO experience since WoW and better in many respects.
Let me just break it down into (+) and (-).
(+) The interface is superior to any other MMO I seen to date. I don't know how else to say it as everything is very well designed.
(+) Graphics are very good as well, with enough adjustments to run well on even so-so machines.
(+) Great tree talent system, with which you can have multiple versions on one class and lots of flexibility to design your own class.
(+) Tons of stuff to do and ways to earn your gear. By level 50 you can: Do PvP, Dungeons, Instant Adventures, Live event Rift invasions, and of course regular PvE questing. All these things earn you different type of credits, exp, for different type of gear and items.
(+) LV50 you still earn a type of experience and a new tree system opens up, so you can keep going.
(+) Easy to group with dungeon finder, PvP queing, and later instant adventures.
(+) Player base mostly is pretty decent, with less kiddies and epic jerks than Wow from my experience.
(+) Not as grindy as Wow is and many others. You level up quickly (this can be good or bad depending on the person)
Now the negatives.
(-) You have to pay per month.
(-) In off hours lower population can cause a real imbalance in PvP at Lv50, New Lv50's don't have a chance against higher geared prestige ranked players.
I would say give it a chance with the free lv20 play.