Total compensation is good, but your base salary will be low. You'll make up for it in bonus and the cost of not having to buy breakfast and lunch. You won't get the bonus if you're on leave (i.e., medical leave, maternity leave, etc) so you'll end up getting a lower slice of your total compensation than you might at some companies that provide a higher base salary.
There is huge variation among managers in the sales organization. Some have no experience managing people, some have experience but still aren't good managers, and some are great.
People who think up innovative new ideas are recognized and compensated better than people who do all the work to implement those ideas. Depending on where you are on the "thinking up crazy new ideas" scale, you this may be a downside for you.
Expectations aren't clearly set in the online sales organization--you can discuss with your manager ad naseum what the expectations are, what projects to complete, etc. but you can never be assured of a particular reward (performance rating, bonus, promotion) for completing everything you discuss. Basically your manager can't promise you anything. This is un-motivating for me personally; you may or may not be motivated by this structure.
Engineering is king at Google--you may develop an inferiority complex if you are not in engineering. They won't even give the same headphones to non-engineers as they will to engineers. I tried requesting them and was denied!
Online Sales and Operations is not very flexible about work-life stuff, such as telecommuting a couple of days a month, arriving late in the morning, etc. It is fine to do it every now and again if you ask permission from your manager in advance and have a valid reason like an appointment. Engineering offers much more flexibility in this area.
