To the OP, yes I have noticed my data usage spiked significantly since I bought this phone. My last phone was an HTC Thunderbolt and average monthly data usage was approx 1.2-1.5GB for the month. Here I am now at the end of my cycle with close to 6GB usage. This is my all time new high record and I am pretty blown away. I honestly can't figure out where it all came from. I use the phone a decent amount initially, but that break-in period where you get your new toy and can't put it down, that ended for me weeks ago. I'm now back to my regular usage of mostly texting, reading articles on the web while I'm out, and just messing around with some apps. So I have no idea what it is that made me use so much more this month.
If I had to guess, it's because I'm coming from a shoddy single core 1Ghz processor device with 768MB of RAM that seriously slowed things down to slug pace and limited my ability to pull data. Now that I am on a quad core 1.8Ghz phone with 2GB of RAM, things move blazing fast. This feels like going from my old Pentium III 800Mhz processor to like a Core 2 Quad 2.4Ghz lol it's huge the improvement in performance and I freaking love it.