It seems that people are so starved for data (or merely terribly impatient) that 4G mobile data can't come soon enough.
I consider how few companies had a 3G presence in the U.S.A. in late 2006 when I got my first 3G data-capable phone and things seem much less advanced for 4G than faux G today.
Given that AT&T and T-Mobile hammer home this message that they have 4G everywhere, and that even LTE itself is not truly considered a 4G technology by ITU, the U.S.A. has very little coverage that's not close to old technologies. HSPA+ can deliver great speeds but supposedly it's inefficient or they wouldn't be trying to replace it.
I remember looking back to the iPhone launch in 2007 and AT&T had little in the way of 3G coverage. Verizon's more recent advertising ridiculed AT&T's 3G coverage. When AT&T realized that it looked ridiculous, they stopped naming places where they had 3G and started telling everyone that they were covered for data access.
I used WiMAX the other day, and if you don't know, WiMAX was the initial 3.5G data technology that was used by Sprint/Clear/ClearWire in the U.S.A. and had thriving networks in several other countries before LTE was available. WiMAX in the U.S.A. was hampered by some really terrible frequency that allowed it to reach a good distance outdoors but not work much indoors at all, unable to penetrate walls with any consistency.
In my experience, I haven't seen much difference between the speed of WiMAX and LTE in this area. Both hovered around 5 Mbps download speed for me, on Sprint and Verizon, respectively. Once Verizon completes their rollout of LTE, that will likely change, as they'll have a similar number of towers, plus a faster technology. Of course, Sprint isn't sitting still and with the boost of Softbank, maybe they'll have some decent LTE coverage by the end of 2013. Maybe, we'll all have some decent LTE coverage by then.
My mobile hotspot supports WiMAX and LTE, plus 3G, so I'm mostly prepared except that Sprint will add a lower frequency once they decommission the last of Nextel's iDEN network, which operates at 800 MHz. Unfortunately, the mobile hotspot doesn't cover Sprint's lower 3G frequency either, so when things get rough, the tough have to pack it up and forget the internet. (I was wondering why my phone had better connections than my dedicated, data-only device. Now, I know.)
I wonder how 4G coverage will change 2G coverage. There are still places where I see no 3G coverage but I understand that AT&T are re-purposing their 2G towers for 4G spectrum in metropolitan areas.
This weekend, I'll likely be on the move and I should pass through Atlanta (stuck on I-75 isn't much of a place to test), where Sprint already has LTE active in some state of service. Whether I'll actually find coverage or not will be interesting. I'm likely to find WiMAX coverage in the Orlando area (10-13Mbps on I-drive!). WiMAX was a mixed bag in southeastern Pennsylvania, Delaware, and southern New Jersey. At my motel in Wilmington/Newark/Christiana Delaware, WiMAX was the only reliable technology. Voice calls were absolutely horrible but I was getting 4+ Mbps from WiMAX in the same location.
If I look back to my entry into 3G data in the second half of 2006 to now, it took probably 4 years for 3G to be strong enough to be considered everywhere. Can we wait until 2015 or 2016?
Update 2013.10.26: It's nearly a year later and AT&T is claiming to have the fastest and most reliable LTE network. Verizon seems to have the most coverage, although putting LTE on 1 tower is not really coverage, is it? Sprint has started their LTE network and they've changed greatly by being 70 some percent owned by Softbank telecommunications of Japan, and Sprint bought Clearwire, of which they were already a majority shareholder and customer. T-Mobile has accelerated their network buildout by buying MetroPCS and their LTE network. Still, it's mostly Verizon and AT&T at this point.