Excellent experience. 5 minutes walk from strip, but far enough to get out of the noise during the night. You have quick access to everything in the MGM Grand (pools, casino, restaurants, parking lots) plus some amenities exclusive of the MGM Signature (like the Signature pools, valet parking, doggy area, patio chairs with fireplace).
The check in was quicker than in the MGM Grand (I did both check in the same day, because my mom stayed at the MGM Grand), same thing with the check out.
Self parking tip: if you want to park the car by yourself or the valet parking service is closed, just go to the MGM Grand parking lot. Then you'll have 2 options. Walk out in the street and access through a door in a dark street or, my choice, go into the MGM Grand casino, then follow the instructions to reach the pool area. At the end of the hall with restaurants and stores, before going down the stairs to the pool access, there's a door on the left that will open with your room key. Follow that hall and you'll be able to reach the Signature tower, avoiding the streets.
Dog experience: my dog was super comfortable at this place. Each tower has a dog area. The dog area in tower 2 was a little busy, because is next to the valet parking and check in area, but the other 2 were empty. In tower 3, you'll have like a little plaza next to the dog area that will provide you extra space to play with your puppy, far from the traffic and people.