I haven't had any problems with it yet (as a single user); I have had weird problems with dropbox when shared with lots of users actively editing files (conferences). Not really apples to apples comparison, true.
After syncing, the GDrive client constantly used almost 500MB (yes, 0.5GB) of memory while Dropbox was always under 50MB (Windows 7)[1]. That's a huge deal for a program that's supposed to be always running.
Also, the GDrive client often crashed while syncing and had problems syncing some weirdly named files that Dropbox handled perfectly.
I hope GDrive gets over these issues soon, since they have some cool features (e.g. webapp integration, content-based image indexing).
The (up) sync time was also about 10 times that of Dropbox.
Maybe they've fixed things, but the experience was pretty horrible all around.