It's free. There's no reason not to try it.
If you're familiar with 4th Ed D&D, you might notice that all of the classes are based on the suggested builds that pretty much every player would ignore. This game does not offer anywhere near the amount of customization that the pen and paper game does (though there is some customization).
I dabbled in all the classes, so I didn't get very far in closed beta. I liked the Cleric the most, and I liked that it was easy to be tossing out heals while also doing damage (he can even shoot lasers like a proper 4th Ed Cleric!). You won't do more damage than a Rogue or 2 handed Fighter, but you're doing more than just tossing out heals. I also enjoyed the shield Fighter, whose block ability prevents all damage. It's a different tanking experience than you get with other MMOs. With both classes, you've got a power bar management system (Divine Power / Block) that really keeps you focused and involved.
Playing with friends made this game very easy, at least in the first 16 levels. As a player of the pen and paper D&D, I was desperate for a challenging fight. As a Cleric, it was all too easy to keep my Rogue friend and myself at 100% through most fights. However, we can go all the way to level 60 now that it's open beta, and I've heard that it does get more difficult. Still, as a D&D game, running solo at any time just feels weird to me.
Although I had fun as a Cleric, I'm going to throw this out there: Healing potions heal for more than a Cleric spell, and you loot more than you need as long as you don't play carelessly. You don't heal naturally over time (unless you have gear with that specific stat), but there are plenty of rest areas that will heal to you full. They wanted you to be able to solo as any class, but I think it really does diminish the Cleric's role in a group. I'll have to wait and see how it plays out at higher levels.
I was really hoping they would have the melee Cleric class by now, as that was what one of my favorite 4th Ed characters was. I am very saddened that I can't remake him in game yet!