I'm playing through Daikatana right now, and I 'm still in the early stages (the sewers), but I can't help but compare it (unfavorably) with Quake, which hit so many sweet spots in gameplay that Daikatana just misses completely.
Does it get better beyond the sewers? I almost feel like I'm doing work playing this game. The only thing keeping me going is just curiosity, and the fact that I really like the setting of the game.
There are four distinctive episodes with entirely different themes, weapons and enemies. First episode arguably is kinda brutal at first because the difficulty wall is kinda quite high. Difficulty doesn't that gradually climb in the game but instead is quite steep instantly actually. That can be very off-putting when you're still only just trying to get into the game. However if you're willing to learn how the game works, it's worth playing imo.
Daikatana is by far not the best game ever made, not even close but I would say it's pretty much a solid 7/10 game. Unlike more modern games, it does not hold your hand and has that thing that Quake etc had.. where you had to use your brain to be able to proceed and solve the actual *puzzle*. It's nice to play a game for a change where everything isn't just being handed to you while walking forward on that corridor with glowing objects. Exploring is also very much worth it since pretty much every level has secrets to be found.
But as warning I do have to state that the game is not bug-free and sometimes a bug may test your temper and because of one, you may need to reload a quicksave to get the situation glitchfree. Yeah another thing is that you most probably wan't play with the setting "Unlimited Saves" turned ON.