working for an endowment?

I'm assuming that you will be working with their in-house investment team - basically chipping in wherever and on whatever they need? 

I would view this offer as very similar to getting an offer from a similarly sized asset manager, focused on a variety of asset classes. In most cases, a lot of the work that is done is interfacing with their investment consultant, monitoring managers or positions, reporting, risk - often times people wear a lot of hats. If you are fortunate you'll get a lot of good exposure to different managers, strategies, options, etc. and start thinking about how you manage a perpetual portfolio. 

As I've said before - Asset owners, the ones who give most of us jobs at the end of the day by allocating money to us, are underrated to get experience at. The caveat is that you don't necessarily get 'direct' investing experience (i.e. picking individual bonds or credits for a fixed income strategy) unless you are at a much large one but it wouldn't be a bad way to get a quick crash course in the world of investing, exposure to a ton of different managers/strategies and probably a good name on your resume. Certainly shouldn't hurt you.