I use GP3 as my main 120 film.
I've not experienced any "print through" problems or any "scum" either.
I get the occasional roll that hasn't been taped properly but it's so cheap I can live with that.
It does curl like a beeyatch though, which I do find extremely irritating
In D76 1:1 it's very smooth looking but lacks a bit of sharpness and contrast to my eye
Lovely in Rodinal 1:50, quite "punchy"
Caffenol, somewhere between the two (but also I've shot rolls at 80, 100 and 400 then developed in caffenol for the same time and got perfectly acceptable results)
If you want to shoot a lot of film but don't have much money, I'd recommend it. But I wouldn't use it if my living depended on the pictures I took.