The Thunderbolt has issues. Seems like every other app in the Marketplace has people screaming about it not working on the Thunderbolt, and every other app update seems to be a Thunderbolt fix.
I have a 4G USB modem and can attest to the problems with 4G, tho they aren't as bad as people make it out to be. When you are in a 4G area with a good signal the 4G is thoroughly impressive. When you are in a 3G area, it's just normal 3G, tho it can take a little while longer (30-60 seconds) to lock onto a signal, mainly when booting up, because it'll search for 4G first, then finally give up. When you are in a marginal area, like when it wants to keep switching back and forth between 4G and 3G, every time it switches it's a 30-6- second delay with no connection. Not a problem, except sometimes it switches back and forth every 30-60 seconds, which makes it worthless for anything other than a phone. There are times when the 4G modem can't find or doesn't want to connect to a 3G tower in a 3G-only area for several minutes, so I'll just tether the phone and be done with it.
But all these problems are virtually the same as when 3G (EVDO) was being rolled out, and you were in marginal areas. The Pilot north of Lexington was brutal and often rendered my phone deaf and mute, no calls in or out, and I finally had to turn of EVDO completely to solve it. But once they finally got EVDO up and running widespread those problems disappeared. I've already noticed an improvement in 4G and marginal areas in Chicago and Dallas as compared to 2 months ago. A huge improvement.
If I were getting one tomorrow, that's a tough call. It would probably be the Droid X2 even though it's only 3G, but that's because my current Droid Original is also just 3G and I also have a 4G modem. The Droid Charge is a strong possibility. It's a nice crisp phone with the same screen as the Samsung Galaxy S2 (which is also one you should look at closely).
If you can, wait on the Droid Bionic which is due to be released. That's what I'm doing. It was slated for Q2 release, but Motorola pulled back the release date a bit to make some more improvements on an already impressive specifications package. It is the first dual-core 4G LTE handset in the States, with a 4.3-inch qHD display, two cameras (front and rear facing so you can video chat), one of which is an 8MP camera, full 1080P HD video camera, an external dock and laptop system.
The dual core processor is important because it's far less harsh with battery life while at the same time providing more horsepower. It essentially doubles the power and halves the battery usage at the same time. The processor is the 1GHz ARM Cortex-A9 processor using the Tegra2 chipset (better than the others), and 512MB of the desktop-grade DDR2 RAM for internal RAM, and external storage is a 16GB SD card that can be expanded up to 32GB. Plus, and this is the biggie, a huge 1930mAh battery (some Motorola specs show a 1750mAh battery, but either is a huge leap forward in a stock battery). So you get dual core, and a significant battery upgrade all in one whack.
It could come as soon as second week in July, maybe end of July, but most likely early August for the Bionic release. That may be longer than you want to wait.