I'll start this off by saying I don't have an iPhone 5 on Verizon, but I do have a Verizon LTE iPad, so this is all "FWIW".
I've been with AT&T since the original iPhone. Switched to Verizon last year with the iPhone 4. Got the Verizon LTE iPad as soon as it came out, earlier this year.
Having gone from an AT&T iPhone 3Gs (which was only HSPA, not HSPA+) and switching to my Verizon iPhone 4s (which is just 3G), I hated the data experience. Their 3G network has lower ping times, so graphicless websites pop up a little bit faster, but their 3G speeds are so freaking slow (it's usual to only see 512kbps on a speedtest where I live, anything 1mbps or faster is a rare fluke) that everything else I did on the phone took forever. Apps would often take 2-3 minutes to download (which doesn't sound bad, unless you're used to the 10-30 seconds it takes on HSPA, or even faster on HSPA+).
On my iPad, the LTE speeds are extremely inconsistent. When you're near a tower were Verizon implemented LTE, they can be 20mbps+ down, which is awesome. However, in this market (which is the largest in VA), they haven't put LTE on all of their towers, so there's a lot of areas between LTE towers were the signal drops below 3 bars, and the speeds drop way below AT&T HSPA here.
Verizon's LTE is inconsistent enough in my market, and the speeds of their 3G network are so incredibly slow compared to AT&T HSPA, I paid the ETF and went back to AT&T for the iPhone 5. They don't even have LTE here and for me, but their HSPA+ is more of a consistently fast network for me here.