Experience is good, you get decent LTE speeds in Chicago downtown and suburbs then again it is mostly dependent on the area you live and work. I get 12mbps down and 8mbps up average with 150ms pings. I never had the mms problem when I ported to new LTE sim and new apn which Iphone users are facing.
But the problem which I face is that I get delayed notification for gmail, whatsapp or any of the apps which use push messaging or Google cloud messaging. If you think about it you ll blame OS/Phone for it but what I read is people are facing this problem on iphone. I did not have this problem on my 1+ year old sim with Nexus 4 or Nexus 5. It started after porting to the new APN.
Not sure what ST are doing, since the data speeds etc are fine on the phone. I am normally on wifi both at work and home so the only time I notice delayed push is while I am driving or I am outside. So I have yet to check it in detail what the problem is.