I have been using the .37 for over a week and am happy with it. My signal fluctuations have went away, but I do notice that after a call sometimes I search for network very quickly, but it comes right back up. Memory leak seems to still be present as well, but this beta seems stable so far.
I loaded the 188.8.131.52 beta earlier in the week and overall, I'd say it's got some nice improvements. There are a few areas that still need work, but nothing that makes me want to go back to the released 4.2.2 version. I've seen some rumors of a .40, but I haven't seen anything to substantiate that. Has anyone else?