I used it back in the day when I still had analog Cable TV and a digital capture card. MythTV was a pain in the ass to setup. The UI was horrible and if you were trying to setup satellite, it could get really complicated if you didn't know what you were doing.

That being said, MythTV is probably hands down the best digital recorder I've ever used. Like for LiveTV it sucks, because channel switching takes ages until it's built a recording buffer. This might be less of an issue on SSDs now, like I said I haven't used in ages. But MythTV had some of the best features in terms of scheduling recordings, avoiding conflicts and skipping commercials.

Once I started using MythTV, I stopped watching live TV entirely. Since I simply just recorded stuff I was interested in.

I've used MythTV, TVheadend and NextPVR. MythTV has the best recording features. TVheadend in combination with Kodi has the fastest channel switching, which is great if you just want to channel hop. NextPVR is decent and IMHO the easiest to setup out of the three. But is lacking in certain areas.