Fourth edition has been highly debated since it came out, in the grand tradition of DnD fanboys and girls everywhere. Every edition isn't as good as the one which came before-especially for the first year or two.
What fourth edition is best at is random encounters. It's a system that's MADE for one shots and minis-style battles, whatever it lacks in the rest of it's gameplay. If you're looking for good fighting fun, 4th edition might be just the system for you. If not, I'd give it a pass.