Good stuff:
- Works well, even with relatively poor network conditions and people located in many continents.
- Sound is excellent, good automatic echo cancellation and reasonable noise reduction.
- Doesn't crash (you'd think this would not be notable, but try Skype some time ...)
Bad stuff:
- User interface sucks. I get confused every single time I try to start a new hangout. There seem to be multiple ways to start a hangout, none of them obvious.
- Can't record a hangout and keep the recording private.
- Privacy of the whole thing is suspect (it is Google after all). The G+ plugin is incredibly invasive, to the point where I have a separate computer entirely for G+ / hangouts and I use it for nothing else.