Alas, I am not currently an owner of a steel boat.
But I have been an owner of two steel trawlers in the past.
Just as in any build material, quality of materials and construction methods are paramount. High quality steel and good discipline with coatings and insulation is a must. When done right I think steel represents a very good build material.
The vessel you are looking at is old enough to reveal if she is the type you want to own. The nice thing about steel is that it is no good at hiding her trouble. Steel going bad bleeds, so look her over thoroughly for signs. Hire a very good surveyor that understands steel and has the best and latest technology in audio guage. Not the grocery store junk.
Compare those results with the build specs. Insulation is also a big deal so that the steel doesn't sweat in places you don't normally see or have access to.
The steel boat I recently sold was two years older than your candidate. She was incredibly sound and bone dry. Unless her new owner is an idiot that neglects her care, I believe she will still be sound and at sea 50 years from now.
At least by the photos, that one looks well cared for.