I have one. It is a great engine, but I don't run it often due to my lack of a layout. It is fairly reliable though, like most prewar/postwar engines with E-Units.
The biggest thing to watch out for is zinc pest. The wheels are notorious for that, and I wouldn't be surprised if the frames get it too (I know the 262e's do, but can't remember about these). Other than that, just watch for typical wear/condition issues that you would expect on an engine that is nearly 90 years old.
Another note: different eras had different features. Mine (a black and green one) has an e-unit with a chugger, though many were build without the chugger. Some of the grey ones have whistles. I think some of the real early black and green ones had the pendulum reverse unit, but I could be wrong about that too.