As someone who doesn't enjoy chess as much as some people, I can't say much about the engine or the arrow tools or anything like that. However, I think lichess really has managed to create something special. There are so many little features that impress me quite a bit, from the satisfying clicks of pieces, the tournaments and modes, the ability to do all sorts of little things on the side.
Like yeah, it's chess at the end of the day, but it's the definitive way to play chess online for free, and that's a really nice thing. I just wish the Bongcloud was mandatory, then it would be a 10/10