Technically, I dont use MBlaze, but really the pocket WiFi router sold by MTS is riding on the same network and concept. It uses a SIM card and claims 3.1 Mbps of speed.
I pay 999 per month to get unlimited browsing with the first 12GB of data transfer at high speeds. I use a BlackBerry Playbook and absolutely swear by the router. It gives me download speeds of 1.5~1.8 Mbps based on speedtest.net results at various times. The upload speeds are 0.7~0.9 Mbps. This is when I am in one location. If I am commuting and use it the speed drops. The reliability is good and it hardly drops. Maybe once in 3hours or so. For many, that is unacceptable. I can live with it.
The worst part of dealing with MTS is their customer support. They dont seem to have a clue and are not trained appropriately. They take long to get back simple answers(I spent 12 mins on the phone today to get a store address). If that is resolved; I think it is a great service.