Hey, thought I'd chime in, I've had my Dx for probably a little over a month now, and it is pretty awesome. I was on the fence in Nov about getting one, as all those rumors were coming in about bigger and better phones, which now haven't really come to the surface and so I'm glad I pulled the trigger on the X.
While the 3g is definitely not instantaneous for web browsing, it's definitely better than no internet at all. Internet pages take no more than 10 -15 seconds at most, and while I could see it being cool with 4g doing it faster, to me it wouldn't be worth paying $10-$20 more that the $30 I'm paying for internet now.
Some other points of interest:
-Some of the options for features are more hidden than I'd like them to be, or organized in strange ways.
-The whole volume system is kinda wonky for me. If I'm about to play a game or use an app I know that's going to make noise, I'd like to turn down the volume before I open the app, but if no app is open it only separately turns down the ringer volume leaving the media volume loud. (There's external apps to control that, but it could be designed better.)
-I sometimes have issues with gps or wifi keeping the phone from sleeping despite the screen being off. (There's threads about this bug out there that offer solutions)
-Battery life lasts through the day, less with "OMG I just got the phone and need to play with it all the time" use. Though I usually give my phone a mid day boost just so I'm not left out late at night with a dead phone.
-Some of the stock phone stuff isn't as impressive as I'd like to see it, but you can easily just go and find a new version if you don't like it. I've replaced the calendar, weather, launcher, browser, sms messaging, clock, and camera with free/inexpensive apps already. And the more you want to travel down the rabbit hole, the farther the phone will let you go.
-I have run across bugs, weird things happening etc., but nothing that a hard reboot doesn't fix.
All that being said, I really do enjoy the phone, especially with all the customization I can do to it (even without doing any of this rom or theme stuff people talk about).