Assuming you live in a high humidity area, condensation will be a factor. Also, code requirements call for the wall and doors between your garage and dwelling must be fire rated. You likely don't have that now and your insurance (and local inspector) wouldn't like it. As part of the fire rating, you may need fire blocking in the wall studs, which would make installing blown-in insulation more difficult since you'd need more holes to get around the blocking.
Changing the use of space needs to be worked out, and it doesn't seem like you did any in the project. Depending on the climate, the vapor barrier location can sometimes shift from the inside wall to the outside wall, so you'd want to do it right for your particular area. Up north, where the perponderance of HVAC is heat, the barrier is towards the inside. Blown in cellulose is good in that it doesn't allow much air intrusion like fiberglass can, but if it does get damp, it will take a lot longer to dry out and is great mold food. You might want to consider injecting with foam which would be better insulation, stop air intrusion, and would (most anyways) act as a vapor barrier as well.
To up that wall to fire code, you'd likely have to either replace the current drywall with fire rated, or maybe just add a second layer. that won't cover fire blocks, if required as well. It doesn't sound like you pulled a permit.