Welcome to the site. What position does player play and is this a school at the top of his list? Are we talking power 5 D1? These are a few key variables. I'm sure you will get some great responses but also be aware that you can search existing threads in this forum and there are many on this topic. Generally...
Some pro's -
assuming school is making significant $ investment, less likely that they will recruit more high profile guys at your position
better chance of finding a mutual match - they are looking for a player like you for position and you are looking at their school as one of your top choices
some mental relief from the recruiting process
Some cons -
you basically take yourself off the market, so if things change, it can be a much more difficult path to find the right school again
If coaches change, which they do frequently, you may be starting all over or in a place where you are no longer considered the preferred player
it is a very one-sided agreement. if you don't progress at the expected rate or if they find a better candidate at your position, they will find a way to "back out".
If your interests change or refine as to which school you prefer, it becomes much more difficult to change directions.
PS - well geez, looks like I just repeated what everyone else said in the last seven minutes. At least we are consistent.