Do it. Do it now. The real-time bother can easily be negated - like in Baldur’s Gate - by pausing the game and queuing orders to your party members. The game does have something of a learning curve, but it’s mostly figuring out how the D20 system works and how the character statistics affect the die rolls. Nothing twenty minutes on Wikipedia’s D&D article won’t give you enough of a primer on, if you don’t have prior D&D experience.
It’s a very good game in it’s own right, and the expansions are mostly all delicious. And the user made modules are unparalelled, maybe with the exceptions of the Elder Scrolls 3: Morrowind mods.
Go for it
(And then go get Icewind Dale 1&2, Baldur’s Gate, KOTOR 1&2, Titan’s Quest and join me in the drooling queue for Fallout 3, if you’re not there already :p)