Remember it doesn't actually know an API or how it should be used: it's putting things together to look like typical code. For me that has meant difficult to spot bugs like linking up incorrect variables from the rest of my code.
I wish it could integrate the first SO answer to a generated question, because I always end up there anyway having to fix things.
I've only had it for about a week now but overall I'm happy with it. None of the code I'm writing is crazy cutting-edge stuff and in aggregate I'm sure it saves me more time than takes, including the time I spend reviewing and potentially changing the generated code.