This game isn't hard to come by extra lives. But I have died. ALOT. Although sometimes I'm just screwing around looking for SECRETS. What's really wonderful is that most of the time, when there's an area that looks like you could reach with some clever platforming, it rewards you accordingly with SECRETS. Awesome.
edit: Oh, and that raft stage in the swamp world is wicked. Its like a full assault of goombas, bombas, piranha plants, koopas, etc. raining down from the sky while you stand on a raft going down a stream of poisonous water. I musta died like 15 times.