I have never personally owned a mini Schnauzer before.. bet I have met ALOT of them. Some have awesome personalities, but some have a slightly more aggressive attitude.. Most are a pleasure to groom though, i find.. My grandmother has owned a couple, but hers are always pretty agressive.. I believe its all in how to train your dog, and socialize him/her from a young age helps ALOT.
Congrats on your puppy, make sure to post pics when you bring him/her home .