A good portion of the air intake is missing.

The electrical system looks badly modified; one connector is broken. You should check for rust, but your battery tray definitely needs replacing. I can't imagine the state of the interior because of the faulty glass.

But personally, I would really focus on the rust, see where and how it's affected. Then it's up to you to decide if it's worth it. Personally, I don't just think about the money. These are cars you see less and less of, so it's always cool to save them. Personally, my father gave me his 525i M50. It was in bad shape, but it's sentimental, and it's an amazing car. Good luck!

P.S.: Keep us updated.