As a fanboi...I'm unimpressed
@fluffy: I got lots of 'unknown errors' when I did my upgrade. It kept failing when trying to connect to iTunes so I assumed it was down to server load. But then I ejected the phone, closed and re-opened iTunes and then reconnected the phone...and it re-activated first time, so try that.
@Matt 40: There's no pictures icon in the camera app because it now displays a thumbnail of the last photo you took. Take a random snap and you'll see.
MMS still doesn't seem to work properly. I still have a random snap waiting to be sent. Rummaging through the settings I see that O2 have changed the APN name for all the iPhone services. It used to be 'mobile.o2.co.uk' but now there are multiple APNs (for data, MMS and visual voicemail) and they are all set to 'idata.o2.co.uk'. Now I wonder why O2 would want to separate/differentiate iPhone traffic in this way...
All in all...I'm not impressed. The extra features just don't really do it for me although I'm cried for want of cut-and-paste in the past so I'm sure that will come in useful. But Safari is now slower and clunkier, even typing text into an input box is laggier than it used to be.
There's no revert option that I can find. And we call it progress.