It will feel like some one is pushing on your teeth. The brackets stick out a bit from your teeth making it feel like you have a full mouth of metal, big lips and your bracket may rub against your lips feeling again like a metal file.
While some breeds may be more suitable than others for a beginner rider, there are always exceptions to the rule. Quarter Horses often make great beginner horses because of their even temperament, but some can be quite hot or energetic for a beginner.
I have helped my friend with her horse and now She is a Barrel racing horse! But thank you again. Training green/problem horses is an *entirely* different thing than training foals or completely unbroke horses. You aren't going to have an basics you build from, you are going to need to be the one to teach those as well.