It's a fairly fun game that should last you a weekend. It's just easy as hell and tries way too much to be similar to the original SMB, ignoring the expansions that the sequels made. I disagree about the replay comment, though. Sure, I had fun during the few days it lasted, but I have absolutely no desire to return to it. I fact, I'm considering selling it.
I'd rent it and purchase something like Elite Beat Agents instead.