Pros

It's really interesting to work at so many high-profile companies and large projects. It's a great place to get experience, and if you really like travel 80+ % of the time. If you're single, or don't want to spend much time at home, it's great! It's a great place to get some high-end experience for a few years, then go somewhere more reasonable.

Cons

Travel 80% of the time. If you live on the west coast, you'll be working on the east coast at some point, etc. It's impossible to take your vacation, get your required training, and meet your utilization target. Something will give, and for many people it's their personal life / family. There have been several PMs and practitioners that I've worked with that have made a career with IBM (20 years) and if they had an offer on the table, they'd leave.

IBM is an 8,000 pound Gorilla that has all the problems of a company that's very large.

Advice to Senior Management

To keep excellent staff, you must treat them well. Most customers will support the consultants working remote part of the time, that should be built into the sales / engagement process. Treat people with respect, be mindful that employees should have lives at home, and really support work/life balance (not just lip service), and your employee churn will go down. Let employees choose the flight that gets them home at a decent hour (especially if it's billable to the customer). Make a real effort to keep employees in their region when it's possible.