Short version: Voynich Hotel is a comedic slice-of-life series that excels at not taking itself seriously, and ends up being a lot of fun to read.
Voynich Hotel is a slice-of-life in a weird setting, much like Aria or YKK. But instead of focusing on the imaginative world of Neo Venezia, Voynich Hotel emphasizes the characters. The backstories of Elena and Taizou aren't tough to figure out, but they comes out one piece at a time, revealed through actions instead of straight-up exposition. In the meantime, these two go through the motions of a normal daily life, but in the midst of witches, zombies, and murderers.
Everything that happens is over-the-top crazy, but Voynich Hotel treats it like it's a normal everyday occurrence. This matter-of-fact attitude makes each interaction strange and unpredictable, and that combination is addicting. I read this always thinking, "how could they possibly react to this??" ...and still got pleasantly surprised each time.
So what's the worst two things you could put together? Great, now combine them and make it work out. That's the whole feeling of reading Voynich Hotel.