I upgraded to 5.0 last week and have not noticed any bugs with the OS to this point.
I am not experiencing the memory leak issue that some of you have mentioned. I am going on day 3 without a reboot and still have about 28MB of free memory.
I have however noticed a significant increase in battery drain - particularly when doing a battery pull. I lose about 20% of my battery on every reboot. My battery is old and definitely needs to be replaced but with 4.6 I could get 2-3 days out of it. With 5.0, I am lucky to get 1.5 days out of it.
With all that said, I do enjoy the new OS and will not be reverting back to 4.6.