Pros
Interning with Enbridge was great. I worked with them during the summer of 2010 as an intern with the off shore commercial development team. It is a large and established company, but you get to interact with management quit a bit. They were extremely excited to have me as an intern, and really looked for ways to get me involved with their work. I came away from the internship with a good knowledge base of the oil & gas industry. Overall, great place to work, great atmosphere, great employees, very talented and knowledgeable management. This company is in good hands.
Cons
Very few cons, this group was always looking to teach me and enhance my experience as much as possible. The only con would be that for this particular internship, there didn't seem to be very many openings for entry level positions.