I know this is just a test release but there are two things that I think need to get fixed ASAP!
First you can't turn it on silent>vibrate>sound. It either always vibrates, never vibrates or only vibrates when sound is on. Seriously?!?! I've never owned a phone that you can't just go up and down on the volume rocker and go all sounds off>vibrate>sound on. If this is in the final release then it really really sucks.
Second, the merged calendars. I use my phone for business and need to see when my next appointment is for work and when my next appointment is for personal use. I HATE the merged calendar. It makes my exchange calendar virtually useless. I am glad they put the signature support (finally) in the native email app but this is one step forward and 2 steps back in my opinion.