General Availability is give or take 52 days away - less than two months so I would emphasis what xandros9 said. For some it has been plain sailing and for others there have been issues. This is due to the insane number of combinations of hardware Windows is being used up on.
However I would exercise caution if your upgrading your main PC on release day - back everything up and clone the entire hdd as a fail safe.
The technical preview for me has not been smooth and I'm dual booting, if I wasn't I would have lost quite a bit of data and time - reinstalling Windows 7 + setting everything up again.
Edit: Oh I see, the OP is talking about phones not PC's - my bad (I blame etphoto! :winktongue: )-
I know its stupid but I've been running TP on my main computer for a few builds now
- had the grave yard shift again :grincry:. For phones the situation is no better, in fact it is worse. The release of phones would most likely more be than two months out given the preview for phones started later and the build we got was no where near what MS had on show. So therefore I imagine they are much more further along however they are drip feeding (not using the the term - "dog fooding" - as some can easily misinterpret that lol) to gauge what users reactions are and incorporate feedback.