I'm not qualified to judge Szell's Mahler 4 as I'm not a Mahler fan, but the fact that so many people cite that recording is testament to Szell's sheer professionalism because, like me, he didn't find Mahler's music congenial. There are other conductors whose best moments get through to me more than Szell's do, but I've come across few whose musicmaking was of such consistently high quality.He's a machine. Yes, but a very good one!
Seriously, I would answer definitely yes. His recordings of a lot of the core repertoire often represents some of the best recordings of those compositions. His precision does help. He also often adopts fairly fast tempi in an era when most of his contemporaries usually went in the opposite direction. I also don't find his recordings to be lacking emotion or pathos.
His Beethoven symphony cycle is one of my favorites, possibly my absolute favorite. His late Dvorak symphonies are, appropriately, legendary. His Dvorak Slavonic Dances are a romp. His late Tchaikovsky symphonies (4 & 5) are great, belying his reputation as emotionally cold. His Mahler 4 is legendary and is my favorite recording of that symphony.