I would be worried about all of it if you are going to be keeping the car long term. You can see looking around the pedals that you have a leaky windshield, so you need to fix that to keep water out of the cockpit. You need to peel back all the spongey floor matting , cut the rust out to sound metal and replace it somehow. It WILL look a lot worse once you have done this, but if you don't you won't have much of a car left in a few years.

Rick

__________________
80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)