Calendar Swamp: Which Outlook/Google Calendar sync is best? is a good summary of the options. The poll shows that Google's solution is the #1 choice of the readers of this hard core calendaring blog.
The Google solution works pretty well for me, though it can sometimes mess up all day events. I've read that this is related to an ancient bug in the way Outlook handles all day events. I haven't read the details, but I'm guessing that there's an old design flaw in outlook, such that an 'all day event' is really a midnight-to-midnight event rather than a 'day event'. This means that a time zone or savings time glitch will cause some events to spill over into another day.