The front nine has no parallel holes, but the back nine has many parallel holes...it reminds me of Firestone South in that regard. I have played Inverness many times, and found it to be a solid, good test of golf. There is nothing tricky about it; everything is pretty much right in front of you. As Will said, the greens are tiny, which emphasizes not only the need for a good iron game, but the need for a good short game.
The history of the place is what makes it special for me. I believe Byron Nelson was the pro there...if I'm correct, that's quite a feather in their cap. I also believe it was the scene of Jack Nicklaus's first ever U.S. Open, and one of Bobby Jones's first Opens, where he was paired with Harry Vardon. Throw in Tway's famous bunker shot, and it's hard not to feel like you're at a place that has contributed much to the history of American golf.