This is my experience with big box store bikes. I live close to the beach and see a lot of cruisers. The cheap ones are OK, they're good to keep around for loaners or occasional use. The problem areas are deraillers, caliper brakes and rear wheels. I don't see many derailler models that are more than 1-2 years old.

If you want a geared cruiser that will last, get an Electra with a Shimano Nexus hub. We've had one that we park outside for 6 years. It's got surface rust on the bars and cranks but it still runs like new.