I hate thumbs up/down. 2 values is too little. I understand that 5 was maybe too much, but thumbs up/down systems need an explicit third "eh, it's okay" value for things I don't hate, don't want to save to my library, but I would like the system to know I have an opinion on.

I know that consuming something and not thumbing it up/down sort-of does that, but it's a vague enough signal (that could also mean "not close enough to keyboard / remote to thumbs up/down) that recommendation systems can't count it as an explicit choice.