What is it like to get a brace for your back for scoliosis?

Not too bad. Most of the new braces are low profile and can easily be hidden under your clothes. There is an adjustment period, usually about 2 weeks, while you and your body get used to wearing the brace.
A committment. Bracing is generally most effective in decreasing the rate of progression of scoliosis if it is worn for >16 hrs per day, and the longer it is worn/day, the more effective it is. They are large and bulky and many don't like them, so it can be a tough sell. Modern braces at least fit under the clothes comfortably and can be hidden with clothing rather effectively.