I have verizon and use the mobile hotspot for all my internet needs. My husband and I both are on one plan. I can't remember what our limit is for the mobile hotspot, but we have never gone over. I have installed a wireless usb router ($35) on my desktop so I could use it as well. So any machine with wireless technology can connect to my phone wirelessly at 3g speed as long as the phone is within the house, up to 3 machines at once per phone. It is faster than dial up or satellite, but not as fast as cable internet (which we can't get here anyhow). My husband and I surf about a minimum of 30 minutes a day each, sometimes double that, for a total of 2-3 hours. We do not do any gaming or anything like that...things like facebook, forums, fantasy football, youtube, itunes are what we do. I do not think it would be able to keep up with gaming or netflix, etc. My husband and I pay $135/month for both our smart phones...which sounds like alot, but we have eliminated 2 house phones and satellite internet as well as a dial up account for our other house. Our plan includes unlimited text/picture messages, unlimited internet (on the cell phone), we share 800 peak minutes a month, weekends/nights/verizon to verizon all being free, and then the mobile hotspot for our laptops/desktop.
This mobile hotspot is amazing and I can't believe more people aren't using it. I know through verizon it is available for free on most smartphones as long as you pay for internet access through your phone.
It works great too, I have no complaints other than it will not work if you are talking on the cell phone.
Edited to add: just found it on my bill, we are allowed 5GB, to share between two phones.