After just having it for a day I can say it's better than my Pre Plus. My house can be a bit of a tester and I've had 3 bars pretty steady. Actual quality call has been good, but I must admit that I only had a couple of conversations. This is a huge step up for me from the Pre.
AT&T stores now have a gel case made for it. It's $25 though. I won't be getting a case as I really hate them, but they also have the screen protectors now which I will pick up.
I have had mine for a few days now and Have used it alot. No problem with the reception on this phone at all. I had the Iphone 3GS before and this is better I think. I did try out the EVO and I will say it is a very nice phone but sprint service sucks in my area. So back to AT&T and the Aria is working just fine.
I have pretty lousy service at my house. Typically around -95db edge signal (guess I ought to look into a femtocell). In the few calls I have made at home, the sound quality is noticeably better than my BB 9700. In strong signal they are comparable. Aria wins in earpiece volume by a bit at a given volume setting.
My Aria has been loud and clear. The speakerphone could be a little bit louder, but overall it's not bad.
My biggest complaint is that I need to find some louder ringtones, I've been missing calls because I'm using a case that clips to my belt, and apparently it doesn't transmit the vibrations. Also, it seems to do a pretty good job of muffling my ringtones!
I previously had a Backflip. The Aria shows fewer bars, but my data transfer has been MUCH better with the Aria than the Backflip. Voice quality has been about the same.
Call quality and reception are great with my Aria. It's the sole reason I chose the Aria over the iPhone 4, coming from an iPhone 3G. Steve Jobs telling me to "hold the phone a different" way led me to the Aria.