Exterior of that grill should clean up well. The problem areas I see are the lid liner and the inside of the cabinet. If that is just dirt and dust in the cabinet, you might be golden. If it is rust, you have work to do but definitely looks salvageable either way. Cook box and everything else on the grill looks solid, just dirty. A quick hit with a pressure washer and some scrubbing and scraping might make that grill look really nice.
It is up to you how far you want to carry the rehab project.