So, i just came back from a (very nice) week in Beijing.
Ordered upgrade to Y both ways with OT and checked the flight loads regularly with seatcounter (while it worked). About 1 month ago, they started giving me "upgrade highly likely" mails. They came with regular intervals, about once every week, so i didnt feel "blastered" as someone earlier wrote this week.
But, after i had gotten confirmation, they continued sending emails wanting me to upgrade to business for "75% less" (than what?). But when checking their webpage, you cannot order further upgrades (guess you must call them?)
Outbound: Got upgrade confirmed 6 days before departure. Flight was overbooked in M (they asked for VDB volunteers), but both Y and C had free seats 3 hrs before departure (the nice checkin agent at ARN gave me the numbers). As a happy surprise, i got op-up to C as well (as a lowly EBS). There was a fair number of upgrades to Y from M as well i think. M and Y full, about 5-6 free seats in C, so nobody got bumped eventually.
Inbound: Got upgrade confirmed 6 days before departure as well. Same situation here, M overbooked. No chances for VBD's though when i asked at checkin. Tried to wait out an op-up, but eventually i upgraded to C with points at the gate and got it immediately confirmed. Y and M full, about 6-8 free seats in C.
Overall: OT did it's job well - since i got what i wanted
But with the unclear system, their nonspecific mail offers, and their (imo) tacky webpage, my general impression is they run a kinda shady operation. Biggest negative is also no Amex payment (as mentioned earlier). But i suppose SAS can vouch for their legimity, so i will use them again.