In its current set-up (mainly the zero-option rough), I would have to agree with Mac that it isn't a great course for the reasons he stated. It is a test only for the elite, and even in the case of a US Open, I'd argue that the rough is overkill, simply because the wonderful greens, slopes and firmness will adequately punish a shot into reasonable-length rough. That's the main reason I'm really not all that excited about this year's event, because the hack-out back to the fairway is boring relative to the failed recovery attempt.
But as I've been listening to player interviews this morning, I've heard most of them describe "options," which I really hadn't considered given the penal nature of the course. But given the relatively short length of the course (when considering firmness or elevation). players can really choose from different levels of aggressive & conservative play. So, in that respect, the restrictions in the driving zones can lead to a positive result (i.e. tee club decisions instead of the default Driver).
Outside of US Open set-up, I was pleasantly surprised how playable Oakmont was in my few trips around. The rough was difficult, but would allow you to make some recoveries (although quite demanding). You really couldn't lose a ball (and if you know my game, that's saying something), and there were chances to be a hero. Sure, the greens were fast, but you were able to adjust to that, with only a few places where I recall it being physically impossible to lag close. I have zero problem with the omnipresent bunkers, as that's the price you play, but there's still a recovery chance.
Having said that, it's certainly not the type of course I would want to play all the time, even with a more reasonable set-up. Penal is simply not my preferred design, and I'd rather have a few more angle options to choose from. I'd prefer a bold green contour punish me for an improper line of attack, rather than thick rough, but to each his own.
I did look back at the Historic Aerials, and noted that the fairways have been narrowed and bunkers moved inward over the past 60 years. As much as the membership may want to talk about Fownes' intent, they seem to have stepped up the demands even more than what was there (perhaps working a little too hard to keep up the "difficulty" mystique).