Pros
Working Hours are Flexible. You can come and go at your will as long as you complete the allocated task for the day. The work atmosphere is casual. Your fellow interns will end up being very close friends. Can wear T-shirts, shorts, jeans all OK. Lots of perks like coffee mugs, bus passes, free parking etc.
Cons
Lack of a proper internship program. Sometimes you may end up idle on your desk for long hours. Tends to get monotonous with hours of similar testing. Compensation could be better. Some people can be difficult to work with which may ruin the work atmosphere.