Pros
If you're the kind of engineer who got into this career because you have a passion for puzzles and solving problems, as well as a love for designing large, complicated systems -- this is the field pushing today's most complicated problems, and Halliburton is the company leading the way with the most difficult. I have absolutely no interest in geology, oil, etc., but the problems the drilling industry faces are jaw-dropping. The first project you get you'll be asked to design something incredibly intricate and sensitive to perform an incredibly precise function. Then you'll be told it's going to be operating in hell where the pressures and temperature are insanely high, it'll be submerged in a thick saltwater mud-suspension, and it'll be slapped on a steel tube that's spinning, holding it thousands of feet underground.
Cons
Job security can fluctuate on a daily basis with the price of oil, but generally speaking people who like their jobs keep their jobs and people who don't are offered a severance package if they are willing to 'retire'. Of course, unfortunate stories exist, but they're not as common as you'd think. Perhaps 1:50 or 1:100 people disappointingly laid-off to people satisfyingly separating.