I've posted a couple other places about my experience in validating classes. I validated almost everything I could and I wouldn't have changed being placed out of courses or into more advanced sections looking back. GPA is important at school, but if you work for only your GPA, you're going to be the most unhappy cadet, unduly stressed, and miss out on a lot of things. I didn't focus on GPA, took the opportunities provided and ran with it. I was a team captain for a competitive club team that traveled almost every weekend year round, volunteered for a youth group, helped establish the writing center where peer tutors help with other cadets' writing, served in a high level cadet leadership position, and graduated in the top 5% of my class with my branch of choice.
The pro's of validating summarized:
1) Open up more course space to take courses you want to take. This is huge with all of the required classes as it gives you more time to do research or an independent study down the road in your major, start a major early, double major, or take courses in other departments because they interest you.. The first two are important considerations if you have aspirations to put together a more competitive application for grad school scholarships coming straight out of the Academy than the typical cadet would be afforded. Taking courses out of your department can just be fun (I took a tactics class for kicks in the strategic studies department because I wanted to, and it ended up being one of my most interesting classes overall. I was a mechanical engineering major; there was no requirement I even come close to taking that course).
2) The caliber of academic potential you end up in class with tends to be on the much higher spectrum of your class overall. Everyone has different strengths, and being a good Army leader doesn't require you to be an academic genius. That said, I walked into classes knowing I wasn't the smartest kid in the room which pushed me to work harder than I would've if I had just been in a regular level course where I could coast. The discussions we had at times sometimes blew my mind at how smart these people were. There also was a strong correlation between those folks being the folks in higher level cadet leadership positions, both in sports and in the Corps' leadership, because there as a correlation between their drive to succeed that carried outside of the classroom.
3) Lighten up your course load, because you have less requirements to meet. I averaged over 20 credits a semester. Being able to only take 4 academic courses one semester was one of the most refreshing semesters I had and freed up a ton of time for some outside projects that I was working on and team participation that I wouldn't have had otherwise. If I hadn't validated classes, this wouldn't have been possible, because I would not have met graduation requirements in four years and I wasn't a Corps Squad athlete.
My final note on the subject, there are very valid reasons to not validate or place out of a course, but West Point is the place to learn as much as possible and challenge yourself to see what you can handle. The Academy is meant to put as much stress and pressure on you in an artificial "safe" environment so you build up your tool kit for time management, faith in yourself, and learn how to leverage your resources to get the mission accomplished at the end of the day. You owe it to your future Soldiers to take advantage of as many opportunities as possible to learn and grow before you graduate so when you show up to your unit, you're as prepared as was possible to be that person, who at the end of the day, might have to make some really hard calls. None of that has to do with what your GPA was when you graduated, your class rank, or even what branch you ended up in. You're a leader at the end of the day, no matter where you end up in the Army, and hopefully you've done everything you can (and continue to do so) to be ready for that responsibility.