Having played both courses numerous times, I would say they are both excellent, but I'd beg to differ with my photographic friend and say neither are truly great IMO.....if "great" means amongst the very finest examples of its kind.
The Upper is infinitely more fun to play. It's sloping fairways and canted greens demand premium shot accuracy. The natural elevation changes and positioning along the flank of the hillside provide a far sportier style of play than it's brutish brother, the Lower.
The Lower (Championship course) lies beneath the Upper, leaving the majority of holes, save for a few, without very significant elevation change. It plays long and relatively tight, although (save for only a handful of holes) not always narrowed by trees. Tee-to-green driving angles are excellent, and not always easily apparent on the box. Approaches are very straightforward and decidedly lack drama.
Some holes permit ground-game run-ups approaches, but not all. It's definitely plays more as a parkland-style aerial test. Bunker placement is strategically superb throughout the course and effectively accompanies each and every hole. Many of them were cleaned-up, re-drained, and often slightly expanded. Their poa annua greens, though internally nuanced a bit, are for the most part, relatively benign....think closer to Bethpage than Winged Foot, Somerset Hills, or Ridgewood. Over dozens plus plays, I've alway noticed that good putters have a field day on the Lower and certainly struggle more with the Upper's. The finishing pair of holes on both courses are terrific tests of risk-reward.
The high thick and stiff rough areas provide the greatest defense to scoring and will continue to serve that role for the PGA Championship. In playing a few rounds this season, I can tell you it's as thick and difficult as anything you saw recently as Oakmont, or historically at Winged Foot. NJ's growing season has been very healthy. Presumably, Kerry Haigh and his team will lower the present heights (10-14") by game time, but the density will remain brutal and exceptionally penal to scoring.
The club, it's clubhouse, practice & training facilities, staff and membership are truly great. The place, as others here have mentioned, proudly displays its competition history and memorabilia. The members, for the most part, are extremely friendly and take great pride in hosting major events and internal competitions. Doug Steffen, their long-time head pro is stepping down this year and will likely never be fully replaced. He is amongst the reigning deities of Met Section professionals and has run the club events with equal doses of congeniality and talent.
Thus, I'd agree the club is unquestionably a great club. I'd say the course(s) are undeniably excellent, but just not great. Maybe I'm a wee bit biased towards quirk and sportier tests (guilty as charged), but when measured against other particularly similar big, tough competition courses (i.e Winged Foot, Bethpage, Pinehurst #2, etc...), the others surpass it for total architecture and form.
Cheers!