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.
Some quarter horses can be mistaken for thoroughbreds - tall, sleek, long legged. These would not be good as a barrel racing horse. You might be surprised, but the average plain jane grade horse is a great barrel racer. Grade is a term applied to horses of unknown origin, mixed breeds, crosses.