MY problem with the speed of this service seems to be every month when my 3 gig is loaded again. It seems that when its loaded I can only connect with Edge and can download nothing! But it seems if the 3 gig is used up and the speed is down to 384 then it's fine again. Can download on average 20 to 30 gig in the month..
Also if you do have the Huawei usb 367 router, get the firmware update for it, running Update 11.810 on 64 bit and that also sorts out the speed problem...
Maybe just try going into your account settings, and change the network type to "3G only" instead of the default which I think is "3G preferred" that did the trick for me.
To the OP, I only ever use mine for downloading, and I download betwen 40-60gb a month, so I'm getting more than my moneys worth IMO. I also had one or 2 weeks where it was VERY slow, but after some investigation I found out the tower near my house was broken, and after repairs was done my throttled speeds were around 320kbps again.