i have a C655D-S5518 with AMD e300 and AMD hd 6310 video card (which i can now remember by heart i have googled it so many times) and my MAIN problems with the FREE upgrade is.,.. no display driver available although if they would give me a free upgrade to win 8.1 they have one for that now
but anyhow only problems i have is with streaming flash it will play with a green screen and sound which is a major problem you can go around this problem by right clicking on the flash properties and unchecking use hardware acceleration although then i have problems with stuttering skipping is the only way i describe it audio/video or sometimes really slow sync problems i'm sure there is a few more i haven't named. suffice it to say it doesn't work well
i have tried upgrading 2 -3 times and tried a fresh install until AMD or Toshiba comes up with new drivers i will have to wait but i downloaded a copy of windows 10 with the media creation tool so i can install when and if they do have one.
if anybody has a fix for this i haven't tried please let me know