They're very fun, and the current metagame is actually surprisingly diverse, if a little heavily-dominated by a current deck known as "Jund." It uses black/green/red.

As far as Zendikar goes, it's pretty solid and has some good flavor. The next expansion, Worldwake, is the second in the Zendikar set and comes out in two weeks or so. It looks very very good, and it will do a lot to change the current meta.