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.
A hot horse is a high energy, ready to go-go-go type A personality of a horse. While I wouldn't say every horse that requires an experienced handler is hot, I would say that every hot horse requires an experienced handler. Hope that helps you.