wimax is long-range wifi (range comparable to cellphones). That modem connects to such long-range wifi that someone else with serious equipment broadcasts.
Afaik, it has a major performance drop when air moisture is above a certain level. Which is a fancy way to say that it sucks when rains. Don't know about your country, but this detail was a deal-breaker for operators in mine.
Don't know if they managed to fix the issue. I doubt it though.
Unless there is someone saying your area is covered by wimax, and you subscribe/pay for such services, it's useless.
Seems like 3G (for the moment) and 4G (for the future) are the technologies doing most of the serious mobile internet.