the only trouble is installing again the pillar cover, not too difficult, but a pain in the butt for 15 20 min
just make sure the anchor on the windshield is the "narrow" anchor because mine came with a wider anchor and I had to file down both parts for the mirror to be installed correctly (what I mean is first take down the original mirror and install the homelink mirror where it goes, if it fits, do the whole installation)
I installed my Autodim/Homelink/Compass just a week ago and it's not bad at all. The A-pillar has a vinyl/plastic bolt that's a little tricky. After I released the two clips so that the whole piece was loose I gently pull the whole piece away then toward the rear and it came off without any problem. There're two mirrors with two different mounts (one is wider than the other). You must check your VIN and see which one you should order.
No one already had the autodim compass mirror or you have to again install more? Reason I ask is my cx7 has the homelink and my MS3 has the auto dim compass. I am trading the CX7 in for a new Mazda5 in a couple months and want the homelink in my 3. I thought I could just swap them...?