Pros
Startup environment with relaxed hours and great team of people. Everyone friendly and skilled. Company meetings were open and forthcoming (mostly). Beer keg on tap. celebrations and gatherings all the time. Strong bond. An ambitious goal. Input from developers usually incorporated and taken seriously. Engineering driven. Decent pay.
Cons
Always trying to raise funding. Product didn't work as well as we hoped -- just too many network topography variables (switches, routers, wifi, LAN, WAN, VPNs, etc.). Useless stock option grants. Stock pool so diluted it didn't matter what your common stock was. On third round of funding and still not profitable. High turn-over rate for developers and sales people (there was a red flag).