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.
Arabians are wayyy to headstrong in general for a beginner. There are always acceptions to this though. My cousin wanted to learn to ride and she is the kind to get everything she wants so she got a pure white arabian as her first horse and got thrown.