Writing's so-so, the animation is nice (if a bit jumpy at places), character designs are interesting, characters themselves are hit-and-miss, the humor's on the low-brow side, but you can tell it was made with love, for what that's worth.
It has it's flaws, and you either like it, or you don't - many fell in love with Charlie alone.>Helluva Boss
More streamlined in terms of animation, and the humor's darker. The pacing is a bit jumpy (there's a clutter of flashbacks in the middle), but the characters can really sell it - especially the one voiced by Richard Horvitz, Invader Zim's voice actor.
It clicks for some people - others despise them.
If you have 30 minutes to spare, you could watch Hazbin Hotel - and Helluva Boss only needs 20 to sit trough.
So, if you have about an hour, it's an okay way to spend it.