But noone plays MP :( !

So yeah, it's very much worth your time. Even if it breaks the save games, and you have to start the game from scratch. But installing 1.3 and breaking the save games is not essential and it will not fix the fundamental issues within the game. But for the multi-player the 1.3 is essential thing.

That's why 1.3 is very much worth your time. 1.3 fixes the multiplayer master server related issues, adds the support for modern resolutions, and fixes loads of other small and large issues. You can read it all from the "readme" file that comes with that community made 1.3 beta patch.

On a single-player side of things 1.3 was designed to make the frustrating parts less annoying and less frustrating and while it doesn't fix the fundamental issues it makes it all a lot more tolerable. Especially for new comers. 1.3 beta contains loads of small fixes especially for Ep.1 which is the worst part of the game. Ep.2 and Ep.3 are the high point of the game. Ep.4 is kind of Ep.1'sh but not as silly. While the Ep.4 hasn't received the elevator shaft fix yet, it's probably coming up there later versions of 1.3. And there are many ways around that issue.

I saw that you played through this 5 times? If thats true, then the single player must not be that bad. I rally want to like this game, but I'm still stuck in the beginning.

I'm going to be honest here. Daikatana's single-player is a kind of a train wreck. When it works it's actually neat idea for a game and insane amounts of fun. But when it doesn't, it's hard and frustrating in a typical 90s FPS fashion with silly level puzzles. The companion bots are half the time amazing, and dumb as fuck the rest of the way. But you probably already know that.

Daikatana's multiplayer on the other hand is a very good reason to play Daikatana in 2014. It's very much like Quake but faster, more weapons, more things to try out, John Romero's multiplayer map design is still up to snuff and probably better than the stuff you can find from any modern FPS game.