Pros: They are shoot well (hop units are very good) and the externals are pretty good (except the plastics on some of the models), generally reliable out of the box.
Cons: They are over priced, especially when you add in the cost of mags. The sop mod batteries are shit and massively over priced. For me the recoil is a gimmick as its more of a tickle. They are a pain in the arse to tech. Spares are expensive. Lack fps out of the box.
For me, on balance I don't think they are worth the money, but each to their own.