I use a couple of local MUPs almost every ride and I sure don't hate them. But you can't use them for training rides or Strava personal bests, and you do have to ride courteously and with consideration for other users.

I suppose it may depend on why you are riding. A very large percentage of my rides are fairly utilitarian in nature, and we have some trails that make it easy to get across town, often faster than taking roads because you avoid a number of lights. I'll also add that some of the trails around here are absolutely beautiful, taking in everything from pastoral landscapes to gorgeous ocean views. Count me in as a fan.