The one's I've flown in were good for two things: instruments, and EPs. They just were high-enough definition to be good for anything else.
I'd add tactics trainers as well, for all of the same reasons and within all the same limitations you can have a good EP sim and/or an instrument sim.
Good:
-Building block/stepping stone for learning "monkey skills" or "buttonology"
-Building your scan- whether it's training your brain and eyeballs which engine gauge/flight instruments to look at for what piece of information you need during whatever maneuver you're doing, or what part of the weapons system display/tactical plot/control panel to look at for whatever you're doing with whatever piece of gear, building a scan is building a scan.
-A good simulator instructor can really
teach you something new and useful whether that's a systems malfunction or setting up different angle on a tactical scenario
-You can try stuff in the sim that would be too dangerous to try in the aircraft
-Less overhead time in the sim when you don't have to read the discrepancy book, preflight, transit to the working area...
Bad:
-No sims that I've ever seen are quite as, uh, chaotic as an aircraft (smell, vibration, heat or cold, radios)
If the flight crew doesn't take the mindset that the event is "just a simulator" they tend to think and act more realistically instead of being distracted by wondering what the instructor expects them to do next. Psychologically I think this is a lot like breaking a student or junior copilot of the "whatever I do in the aircraft my big brother can save us" mentality.
But Rocky and Phrogpilot already knew all this