I've played Riviera 3 or 4 times. I think it's great, one of my all-time favorites.
The recent Confidential Guide rankings are 9-9-8-7. I can't believe Darius Oliver gave it a 7. It's nice and big; the rough is kept at a reasonable length. You can hit driver with impunity. The greens are tilted down to the bottom of the barranca in a way that confounds and delights.
Many would rather play Merion, but with the way Merion is maintained, with 4-6" rough, Riviera is more fun to play. Plus, Riviera arguably occupies a unique setting for a great course.
It's interesting that the least discussed, or most criticized holes, are the long par fours on the south side of the property. Nobody says much nice about holes 7, 8, 12 and 13. There are few negative comments about any other hole, except perhaps the 1st hole, which some people regard as mundane. Personally, I find the use of the little swale that cuts through the 1st and 11th holes to be perfectly placed, and I like the idea of a birdie hole to start the day. And the first tee environment at Riviera is unbeatable.
I am less enamored with the 10th hole than those who consider it the greatest short par 4 in golf. I think it's fantastic, but also think there are better ones. If lowest score were always my goal, I would play the hole the same way every time, regardless of pin position. Fairway wood way out to the left, sand wedge to the green, and hope for the best.
On the other hand, holes like 4, 5, especially 9, 14, 15, 16 and 18 are right down my alley.