What's wrong with it? Many of us have had a (the same) spring in one or more fail and if that's all it needs you don't necessarily have to replace the whole latch, can just swap the spring without pulling the latch if you have dexterity with needle nose pliers and patience.
With that spring arguably being the weakest link, the Doorman may have as good a spring as any other, though last time I checked, the official ford part was about as cheap on Amazon... though Amazon prices can fluctuate like crazy, it could cost more or less there now.
The official Ford part is the one we all had stock that had the spring fail, so I'm not quite suggesting it's the BEST option either... if they had merely rounded the corner on their stamped steel pieces that spring goes on, it probably would have lasted multiple times as long. The spring doesn't (at least not on mine or other pics I've seen) corrode any, just wear related failure from pivoting on the sharp corner of the metal it's attached to. If there were a reasonable way to do it, I would have filed and sanded the corners smooth.
Edit: You don't list your location so I don't even know if Amazon is available to you. I often assume (sometimes wrongly) that people are in the US.
Here's the sticky topic on door latch replacement:
http://www.explorerforum.com/forums/showthread.php?t=170619