I use it mainly to get some nice tube-like overdrive when using my old Musicman amp (with solid state pre-amp) or when using my Carl Martin Rock Bug (amp/speaker sim) with headphones. I also sometimes use it with an all-tube practice amp. It sounds great with all of them.
I also use it before my fuzz which gives it some extra midrange that I like sometimes. Note that the Alberta, like most T-Rex pedals, have FET bypass switching and not true bypass. This may cause problems if you run a fuzz after the Alberta, but my Zvex Fuzzolo fuzz has an internal switch to change the input impedance so it works fine for me.
I use it both with humbuckers and P90-style (SD Phat Cats).
Overall a really good overdrive. It's out of production now, I got it new for half the price, otherwise I think it was a little pricey.