I think this is great for HTC, HTC is really good on hardware, and are only really struggling with marketing their phones, partnering with Google is almost a no brainer
Google's strategy is to make something so good that they don't need to market it. This harkens back to when Google won search. I think they've done alright with this strategy, whereas whenever they try to 'go mainstream' with glitzy marketing and big vision (thinking of Google+ here) they usually botch it bigtime.