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.
Choosing a horse is a personal decision but several factors are important when making your choice. A good dressage horse has a good character, should be a willing learner and have three clear, rhythmic gaits: walk, trot and canter. Ideally, he should fit you, as a rider, in temperament, level of training and size.