I've had this bike since last May, only have about 1200 miles on it, and the LBS says it needs a new bottom bracket. It was making a popping noise when I pedalled hard, and the mechanic says that I've simply worn it out. He says that big riders like me (6'3, 235 lbs) put quite a bit more strain on a BB, and that this is actually pretty high mileage for a comfort hybrid bike.
Even taking into account the fact that it's a pretty low end bike (Giant's cheapest model of Cypress), 6 months and 1200 miles seems like an awfully short lifespan for a bottom bracket. He's replacing it under warranty, so it won't cost me anything, but now I'm worried that 6 months from now I'll have to replace it again - and then I'll have to pay for it myself.
An interesting side note - the mechanic said that this BB is the longest he'd ever seen. He's having to special order it from Giant because he doesn't keep anything that big in stock. He says the frame is wider than usual, then with the triple chain ring on the bike it must have led Giant to use an extra long bb. I'm not sure how it could be relevant, but is it possible that this extra length has contributed to the shorter life?