I live in an area where I travel through the middle of nowhere during my commute to work. I always lose data and voice for about 20 minutes each way. Plus, where I work does not have 4g yet, but where I live does. I've had nothing but problems switching between the two, so now I leave my preferred network on 3g and use Wi-Fi when I'm home.
Occasionally, I check 4g while I'm home or when we leave the house but stay in the 4g area. Last time I checked, over the weekend, no 4g, even with a battery pull and sim card trick.
I think I'm done worrying about 4g for a while. I'll check it on occasion, but it's just not worth the frustration for me anymore.
Heard an ad on the radio for US Cellular 4g in this area now. If it wasn't for the family plan I'm on and their lack of phones, I'd have already jumped ship. US Cellular is really the only truly reliable service I've seen out here...