I had serious issues when first upgrading... but I did a (second) full wipe and format from CWM. Now the latest official is the first time this phone has ever been actually functional for me. Modem signal is very stable now (never was before) and wifi reception is improved.
I know a lot of people are reporting issues and connectivity problems, and I had them too, until doing the wipe/restore/upgrade properly (or maybe it was just running it the second time).
In fact it does so well now I (almost) regret getting a newer phone...