I've had my 220 for a few years, the bluetooth stopped working after just a month or two but everything else has been fine.
To the person who asked, I'd expect my watch to work for a very long time. 10 years maybe? Why not? It's a watch with solid state components. I'm not trying to download any crazy software with it, I'm not trying to browse the web, it shouldn't have virus issues. How long do GPS units last in cars?
I've already replaced the band once. That was trivial, they sell kits to do it. I expect the battery to need to be replaced eventually. I don't know how many charge/discharge cycles it can take, but I probably charge my watch every other day on average so I've done it hundreds of times already, maybe almost a thousand. But you can replace the battery pretty easily with a phillips screwdriver.