When the GS first came out there were a lot of problems and I stopped using it. I think they have done a lot of work on it, but I don’t know. These days I turn to Dreamhost for simple shard hosting. Easy, cheap, and excellent customer service. If you need something more than what DH can give, you should probably be looking at a dedicated solution anyway.
I am currently using the MT (dv) 3.0 for some projects, and am happy with the overall level of service. I also upgraded one to 3.5 and it is pretty nice. I may give the GS another shot, but probably not.