I live in Garland and work in Allen so my commute covers a lot of ground. In my 17 mile commute I'm on lte 90% of the time. Not exactly the fastest connection, between 4mbps-16mbps. In Allen where I work things have improved. During the first few weeks I was unable to get a signal anywhere but behind the building. Then a few weeks later the front of the building. Now I get lte indoors in most places, except the dead zone(still think my work is blocking signal somehow).
So my experience is it has been improving, slowly but surely.
Now I'm unlocked and rooted so I have changed my lte scan intervals, for both scan timers, to 1. This means it checks every minute instead of the default 30 minutes. This is a huge change that everyone should make. You don't have to be rooted although it makes it easier to get your msl code needed to have access to change these settings.
I have had people tell me they have called Sprint and was given their msl code to change this. Your experience may vary. Just tell them exactly what you're trying to do and they should give it to you.
Here is a screenshot of the timer menu so it's clear...
http://db.tt/MZ0sqCKJ
Sent via LTE from my Evo LTE s-offed by an overweight panda.