Ads aside, what's been infuriating me lately is that YouTube seems to have degraded the quality of existing videos and locked the previously available quality behind the "1080p Enhanced Bitrate"; I have no way of confirming this since I obviously don't have Premium, but I'm fairly sure that the regular 1080p of old videos that I rewatch from time to time (uploaded 2-3 years ago or earlier) is now worse than it was. If it was about new uploads with something previously unavailable, it would've been somewhat understandable. Something also tells me that the paid tier is also going to get ads eventually.