Pros
Usually lots of room to advance if you want to work at it. If you can get into a store with a good manager, you'll likely be working with higher quality coworkers as well. Installer Service Specialists easily have the best job in the store; banker's hours and don't have to deal with much retail. If you know your parts and have people skills, it's a great job to have.
Cons
Middle management is largely in charge of things, and they're so far separated from working in a store that they only make decisions based on how things look on paper. They're overly focused on payroll hours and related sales and not focused at all on quality of employees or proper training for those employees. A store that puts $15k in the bank every month isn't allowed to staff properly to cover training, holidays, employee vacations, etc. Compensation is generally meager, until you get to middle management. Gone are the days when being a professional parts guy could support your family. If the company was willing to pay me adequately for my knowledge, I'd still be working as an ISS and not working part-time while finishing a degree. Raises for employees who work hard are entirely too difficult to get. Often they're shot down by DM's who don't want to increase payroll. I see store P&L reports regularly, and I know there is often money for appropriate raises when DM's claim there isn't.