I spent three days at Pronghorn 2 weeks ago -- played two rounds at the Nicklaus Course and walked a good portion of the Fazio Course.
It poured rain the night and morning before my first round at Nicklaus. In fact, it rained right up until I reached the first tee (actually the 10th tee, b/c they sent us off on the back 9 first). From then on, it was completely dry. Even with a large amount of rain, I didn't feel like the course played overly soft. There were a few places where standing water was an issue, but overall I was impressed with the way the course drained and the overall firmness of the fairways and greens. By the next day, the course was completely dry and firm.
I agree with Matt that the Nicklaus course appears a tad too narrow. However, in my experience, it didn't play that narrow (Full Disclosure: I drove the ball very well (for me) during my first round and less well my second round). The narrowest fairways seemed to be #15, #18, #12, #5 and #6. If they seriously plan on opening the course up to public play, I think these holes should be widened a bit to keep the pace of play up and make the course more enjoyable for high handicappers.
I think it's interesting that people love the par 5 15th. While I thought it and #14 were the most spectacular looking holes on the course b/c of the views of the Three Sisters in the background, I found #15 to be pretty one dimensional. After a decent drive over the lava outcropping, you either have a blind second shot to the green with lava rock on both sides or wedge, wedge. For my game, wedge, wedge made a lot more senses than risk a lost/unplayable ball pin high. I also didn't see any benefit to laying up right of the middle bunker 80 yards short of the green. Personally, I found #16 much more interesting because it forced you to decide whether to play short of the cross bunkers or try to fly them on your second shot.
I really enjoyed the par 3s, especially, #3 and #7. For #3 I loved how you could either play straight at the green, or land it short over right bunker and let the slope run the ball onto the green. On #7, I loved the huge false front. It demanded a precise tee shot without requiring a lost ball penalty.
All-in-all, the Nicklaus course was a very good course with a lot of fun holes. I haven't played Tetherow, Fazio, or Crosswater, but have played Lost Tracks, Sunriver-Woodlands, and Sunriver-Meadow. Clearly, Pronghorn-Nicklaus is far superior to those courses. For Oregon, I would rank it well behind the Bandon courses and maybe a shade behind Witch Hollow, but easily in front of Ghost Creek.