I am absolutely loving the boss fights in Last Epoch. They really force you to keep alert and use your skills wisely. They really put the action back in Action RPG. In my opinion, they are the most enjoyable boss fights in any ARPG I have played.
I was just playing my second character (hardcore) and got taken out by the Wengari Patriarch/Matriarch. I was doing well but got caught with my ward down and was hit by one of the leap attacks that took me down. Losing another character felt bad (have yet to finish the campaign, as I prefer jumping in with hardcore from the start), but I felt like I deserved the death, and I felt that if I were a better player I would have been able to dodge the leap and survive.
I hope as LE evolves, the devs can keep the feeling of these exciting boss fights. For me the boss fights are definitely the selling point of LE. A boss fight centred end game activity could be a fun addition in the future as well.