Thanks to everyone who chimed in on this thread! I'd like to report back after my inaugural visit.
I am happiest as a golfer when a course (and club) are giving me a unique and genuine connection to a local ecosystem and/or the local community. And walking off the last green at Portmarnock, I was a very happy golfer.
This is a course in a beautiful Irish estuary. And from the first brackish breath out of the taxi to the last hole of the Blue nine, I was glad to be surrounded by the many residents of this estuary. I can't think of a better course for birding - gulls and crows, yes, but also ring-necked pheasants, larks and sparrow, oystercatchers, white wagtails...the list goes on. The club's logo features a lapwing, and perhaps the day's only disappointment was not spotting one myself. Littered throughout the course I found fascinating evidence of a thriving ecosystem: beautiful clam and mussel shells, neatly split in two and pecked clean. Half-consumed rodent and amphibian carcasses. I was stopped in my tracks by the variety of fungi growing in the rough areas - a few mushrooms were large enough to serve as tee markers! As for the grasses and other flora - they were varied and colorful and perfectly unpredictable without being punitive or claustrophobic (I shot 90 from the members' tees off a 12-handicap but didn't lose a ball all day).
Amidst all this raw nature, Portmarnock also connected me to the local community in a couple of surprising ways. The horizon views (and aiming lines), particularly on the front nine, are often across the estuary to the smokestacks and commercial buildings of greater Dublin. And the birds weren't the only flying companions I had during my round. I must have watched 30 different airplanes descending into Dublin airport right over the golf course. Aer Lingus, Emirates, Ryanair....a constant stream coming from all over the world to this bustling and rapidly growing capital city. I was told by one of the pros that just 15-20 years ago, Dublin's population was half what it is now, and the industrial scene across the estuary was nothing but rolling farmland. These man-made scenery pieces were more interesting diversion than annoying distraction. Why? Because they made sense for the place I was visiting.
And of course, the golf was excellent. Hard to find a weak hole, and it's a testament to the architecture that so much excitement is created even without the benefit of dramatic micro/macro land movement or monstrous dunes. It made me wonder - is Portmarnock equal to Royal County Down, setting aside scenery/dune size?
I preferred the Red nine (especially the stretch from 3-8) to the Blue, with #4 as my favorite hole. The stately trees presiding over the right side will be a lasting memory, and the strategy is engaging. Flirt with the bunkers/trees up the right, or risk a gradually more obscured view of the green as you bail further left. The front of the green is open for a running shot on this long par-4, but if you're like me the slope of the green might take you all the way off the back, where you will make double bogey.
For anyone who has not been, I can highly recommend it as a "must-play" if you are in the Dublin area! And for those who have played it, I would love to hear more memories and analysis.