As many have said before it depends on where your at cause I've saw sprint "LTE" on some vids on youtube and it goes pretty fast. Guess it just depends on where you live at but I have a 4s on sprint and that things is so slow on 3g I just want to throw it out the window but on wifi no probs.
Sprint's LTE is weird. I get LTE at my apartment, but on average I get about 5 mb/sec download. Went to the grocery store about 5 miles down, got 22 mb/sec, consistently.
Sprint's 3g service is consistent all around though.....absolute crap. If i'm in a 3G area with no wi-fi I dont even bother using the internet unless I have to.