I was a little hesitant to get the X because of the low volume ringer issue I was reading in the forums, but as it turns out I can hear mine just fine.
My last phone (and first smart phone) was a BB Tour, talk about complaints and issues, if you paid attention to the forums on that one none of them had a usable trackball, but mine was just fine, in fact the phone worked flawlessly for me.
That said even though the actual phone worked fine it just wasn't the right one for me, screen was way too small and the browser was a pia, not to speak about slow.
The DX is by far the best phone I have had, it is everything I had hoped the Tour would be and way way more. Phone call quality is excellent and I'm in a flaky signal area.
I have had it for 4 days and have not had one problem. Just be sure to read all of the tips here and you'll be doing fine in no time.