I bought a used NeoAir, it developed a small leak on a seam, I tried to patch it, and failed. Cascade Designs sent me a new XLite as well.
Staehpj is right on all counts, it's fantastically light and comfortable, and the noise thing doesn't really bother me in use. If you want something light, it's hard to go wrong with the NeoAir. If you find the noise bothers you, a pair of ear plugs is a great multi-use item.