I was on-site dealing with some non internet related issues when said client's DSL went down (and up, and down, and up. Poor saps still have AT&T. Yuck.). Anyhow, I had to USB tether the phone to download some drivers and such, and was able to get 1.5Mbps while the supposedly 6Mbps DSL was able to manage about 600Kbps. You tell me if you think that's slow on Sprint's network.
IMO, network speeds are just one of those things. With landlines and wireless Verizon just invests that much more into infrastructure than the competition and (out here at least) it shows. I get acceptable speeds with Virgin, but nothing amazing like I got when I was playing with a VZW PC Card a few years ago.
If you're seeing lousy speeds that is very likely due to a weak signal which /will/ drain your battery quickly. The more people on a CDMA cell the louder each phone's got to talk to be heard (vs earlier GSM stuff where only one phone talked at once). Thus lots of people = network congestion + increased battery drain. That's just how it goes.