Bookworm: Definitely no violence. (For the record, I love the LotR books but turned off the movies because the battle scenes and creatures were disgusting, FWIW.) There is, well, innuendo and some language. I’ve never read Infernal Devices, so I can’t compare, but there are people here who will read Discworld and not Hitchhiker’s Guide. (I’m not sure why, but there you go.)
I think this comes up earlier in the thread- I’d suggest reading through it for a pretty good (if somewhat long…) idea of what Discworld is about.