I can't speak to how it works in a Mooney because my Ovation has a GFC-500 but I had an Aerocruz 100 in my former Cherokee 235.
Worked as advertised. Certified versions have no auto trim feature which is a PIA as it is constantly asking for retrim (you'll figure out how to deal with that after a while). It's OK, not great in moderate turbulence - making sure your ball in centered helps a lot. Even though it's not cetified for coupled approaches, it flies them just fine. Please note, this AP will only work on GPS (internal), GPSS (external) Track Mode (which uses its internal GPS for ground track) or heading more (provided its connected to G5 or similar). It will not fly ILS, LOC etc. GPSS roll steering works well.
If you're installing an EFIS that it supports (make sure that its supported..) then you will need to add an A-B switch for input so you can fly heading mode and also use the Efis Baro setting, otherwise the only way to set Baro in the unit is to manually dial in you altitude, which can be challenging in turbulence and a PIA if you are getting a lot of Baro changes.
Here are a couple of review videos that are helpful: