I didn't watch the Creighton game, so I don't have a point of comparison. But still, a few thoughts:
I didn't think Buchanan was as disappointing as a lot of people here seemed to think. Maybe that's because I looked at yesterday's game differently, or maybe it's because I had lower expectations for him. On the defensive side, he wasn't great, but the effort was there, and we know that it takes a while for the bigs to learn Iowa State's defense. On offense, he didn't have much of an impact, but he did have 3 assists, which is nice to see, and he wasn't freaking out with the ball in his hands. Hopefully he can expand his impact as a roller, but that might also come when Tamin is back as a P&R ball handler.
Mulder's impact during the season should be pretty similar to yesterday--a high-effort player who knows how to get easy baskets on offense. Pleta was a bit more disappointing to me, because I just didn't see anything especially interesting. But he should have more room to grow than the other big men, since he's in a new country playing a new style in a more physical environment.
I liked the guard play, though I was disappointed to not see more from Batemon and that Milan couldn't assert himself more. Toure and Nelson were positives, and I like the aggressiveness they have on defense. As another poster said, it will be interesting to see if teams give them the freshman-year Lipsey treatment at the three-point line. At the very least, they both seem more willing to take threes than Lipsey was that year. Hopefully they can make them at a 30% or higher clip.
It looks like Otz played two big men less than I expected and less than some of his preseason comments might have indicated. Jefferson, Buchanan, Mulder, and Pleta combined for 64 minutes, leaving 16 minutes that were played with Momcilovic, Heise, or someone else at the 4. I can't say that surprises me a ton--Otz has tended to lean on smaller lineups when the offense isn't flowing, and I think that may be the case somewhat often this year. It could be important this season to keep at least two guys on the court who are willing to shoot from the perimeter at a higher volume (Milan, Heise, and hopefully Batemon) to keep the defense spread out, and it will be hard to do that with two big men on the court all the time, especially if Toure and Nelson are also commanding notable playing time.
Overall: A lot of positives from yesterday, and definitely some things to grow on. It will be interesting to see what the team looks like with Tamin back (hopefully he comes back and stays back). And I'll echo the reminder that other posters have made that the team will change a lot over the course of the year, especially with three freshmen looking like they could be significant pieces of the rotation.