Primarily an advertising delivery app. Ads appear every 3 videos as you scroll, and ads will run at either end of 90% of videos. The recommendation algorithm is suspect; watching one video could heavily alter your recommendeds. The app has an autoplay feature that plays videos, muted; you could start seeing changes to your recommendations without knowing why! And "Would you like to try YouTube Premium?" pop-ups, whenever you re-maximize the app. Your phone's browser may be a better experience.