Pros
You can get hired with minimal experience. The company culture is big on being nerdy and casual. You don't get hassled for calling out sick. Essentially, it's a step up from fast food and retail jobs.
Cons
While the pay is a step above retail and fast food industries - it is crap for the tech industry. Starter positions pay well for what they are, but advancement is difficult, requires a lot of time at the company, offers little to no pay increase and is often given to people who buddy up to management. Management itself is very, very weak. This company grew in size too fast with too little preparation for leadership. Most of the supervisors and managers were not hired because they make good supervisors or managers, but instead because they were the best at what they do in their department. There is zero quality control, so most departments have huge, frightening problems that specific managers turn a blind eye to and will go unresolved. TL;DR If you have the experience and drive to find a real job in the tech industry, then don't waste your time applying to Sonic. If you have no or little experience and want a cozy place to work while you learn more about the industry and brush up your resume, then Sonic is a much funner company to work for than most other starter jobs.