Pros
Pay is competitive. Nice insurance and investment program. There are still some smart folks left, but it's getting thinner every day. Lots of vendor "lunch and learn" sessions. IEEE participation. Good internal classes, when offered. Fun downtown Chicago location (once you spend the time commuting there every day.) Vacation gets paid out if not used. Tuition reimbursement.
Cons
All work is hyper process-driven, and the credentials are awarded subjectively by "process owners" who protect their turf. A licensed professional engineer may be required to stamp drawings that s/he is not "qualified" (by S&L processes) to prepare. Much time is spent following procedures and justifying every calculation to the Nth degree, rather than focusing on getting the job built. Superstars and slackers get the same performance reviews. Cronyism among partners and their "little buddies" is pretty common. Innovation is discouraged, they just want repeatable error-free work. Junior engineers get minimal exposure to actually building substations, power plants, etc. The best people started in construction or utility themselves before coming to S&L. Private cubicles are rare, usually noisy open "quads" with minimal storage and room to spread out drawings - makes it very difficult to concentrate. No refrigerators or free coffee in the break rooms. No working remote. Antiquated homegrown IT department is completely disconnected from the real world.