West Point's acceptance rate is about 10% and the six year completion rate is 82%, which is higher than a lot of comparable colleges. They used to plan on flunking out a certain percentage of cadets each year, but have switched to a supportive model where they try to get them through rather than flunk them out.
To get in the applicants have to pass a very rigorous medical exam and fitness test. Almost any medical issue will get you rejected. If you develop a medical condition while there you will be declared medically unfit for commission and may or may not be allowed to complete the program and graduate. If expelled for an honor code or military law violation the family has to pay back the cost of attendance (about $70k per year IIRC). Cadets are legally members of the Army and are subject to the UCMJ.
Getting the congressional sponsorship is pretty automatic. Members of congress can approve as many applications as they like, so they're not rationed.
The location on the Hudson River is spectacular but somewhat remote. The village adjacent to WP is little more than a collection of pizza and fast food restaurants and it's a huge PITA to get into NYC from there.
We live fairly near WP and go there pretty regularly for various things, including crew meets (they very kindly allow DD's crew team to use their fabulous facilities occasionally), shows at the theater, etc. and I know several alumni. Football is a religion there and thousands come for the football games.
Another benefit - a guaranteed job at graduation! We thought about it for DS but it's a bit too regimented for him and he has no particular desire to serve in the Army.