For me the game is unplayable when something hinders me from being able to fully comprehend the plot progression. In this case the issue (besides all the other minor bugs that I more or less can overlook at times, even though they're really annoying) that renders my game unplayable is the graphics quality. It got way past unejoyable when I realized that I had missed something important because I was unable to see what a certain object was. The point is, unplayable is different for everyone, but some things are easily recognizable as unacceptable at the very least, for an AAA game claiming to work on all platforms, with MINOR differences.
That's kind of the reason I just dropped it and haven't bothered with it since. Stuff like the ground items that are so tiny you'd need a microscope to see them*, to the poor quality of the port in general - stuff like the potato people in the cutscenes, important moments ruined by textures so low quality that would be out of place in a game from fifteen years ago. When it's bad enough that someone with my vision notices that it looks bad, there's a problem. Then there's the cutscene stuttering/freezing/speeding up bug that wasn't fixed until the first patch like a month and a half in. Sure, it's A-OK to ship a game with a bug that screws up major plot scenes, right?
* I know they "fixed" this in a patch, but one of my pet peeves in a game with a minimap is that you're pretty much always going to be staring at the damn thing. The items being highlighted there makes it worse, not better. Honestly, the developers should have taken a cue from Witcher 2 instead of just aping it without even touching the damn thing. There, even on the 360 port, the items on the ground are not only larger, but the glow is noticable and doesn't fade into the scenery like it does in DAI.
I know AAA developers rely on "Ship now, fix later" but it gets kind of ridiculous after a while. I might forgive it from a smaller publisher/dev team, but this is EA/Bioware, who damn sure isn't lacking for cash. There just isn't any excuse for the way the old gen version was shipped, the lack of support it's received since, the lack of support the buyers have received since, and the way the marketers/developers basically flat out lied through their teeth about the port itself.