Nope. Much better than 1.5 IMO. The spell checker alone is a marvelous addition. No crashes here, and the memory leak problem seems to have greatly diminished.
The spell checker freaked me out while posting a comment on this very forum. I had forgotten about it being added in the new browser and all of a sudden there were these red lines showing up under words I was posting. Thought FR had upgraded until I recalled the features I had read about for FF 2.0.