Usually I upgrade to the latest OS as soon as possible. I bought Snow Leopard for my previous MBP the day it came out. However, I have yet to upgrade to Lion, but it has nothing to do with stability issues. I was planning on upgrading soon, but with the announcement of Mountain Lion coming out over the summer, I'm not sure if I really need to upgrade now.
I really do wonder if there will be a straight upgrade path from SL to ML. Do you guys think that information will be revealed sometime soon, or much closer to official launch?