OK, so I should start by saying that they did make things right, but dealing with these guys is a nightmare! Save yourself the stress and go with someone else. Here's my experience:
1) They fire off a quick quote over the phone. This should be a red flag.
2) When they showed up, the price had gone up by $500.
3) When I called Jack about it, he just yelled at me and wouldn't honor his original price. Luckily the electrician who came out worked with me and got the price down to only about $200 higher than my original quote.
4) They were clear that they were going to permit everything. I later did another job and the inspector came out and held up the job because Cornerstone never pulled the permits.
5) I called Jack to get him to get the permits he should have gotten in the first place and of course he yelled at me some more.
6) He pulled the permit and the inspector came out and failed the inspection.
7) I called Jack to tell him about it and he yelled at me some more and ended up hanging up on me.
8) About an hour later I did get a call back from his electrician who came out and fixed the job.
In the end they did make it right, but it was an extremely stressful and shady experience. This guys is an unethical, loose canon who will do the work illegally and yell at you along the way. The unpermitted work will likely come back to bite you at some point. Save yourself the nightmare and use someone more ethical!