looks like they made a pan out of flat sheet then braced it with angle iron. Structurally, it could be ok, but personally I'd rather have a correct 'stamped' floor pan.
Maybe my moniter's not getting it (likely) but I can barely see anything. But if is a boogered-up floor, I'd be leery of it and any other repairs. I treat rust repairs like lawyers treat witnesses: if you catch them being less-than-honest in one area, what about the stuff you don't yet know?