Went to an author signing last year just after Alloy of Law was released, he did a Q&A and is a genuine geek. At the signing, he mentioned that as soon as he was done with the last Jordan he would start writing book 2 of the Stormlight Archive. It would have been nice, like you mentioned if we saw a bit more of the world in Alloy, but for a novella, it was pretty great. Hopefully we'll see/learn more in the next offering.
The Way of Kings was a pretty great read for a first novel in a series. I never finished Robert Jordan either (got about 4 books in and said no more), and Sanderson is a much more polished author than Jordan ever was. It has some pretty memorable moments.
The one thing I do like about Sanderson, is you can see how he evolves his craft from novel to novel, I think he progressively gets better and better and has yet to hit his plateau as an author. As you mentioned, he won't have any problems keeping the scope in place for this series.
Sure a couple of the characters suffer from cliches in WoK, but I think the way Sanderson spins it is ok. For what it's worth, he is a very prolific author in the vein of Gemmell, and releases books like clockwork. I think it may just be my favourite Sanderson novel to date. After having worked in a bookstore for almost 10 years, I've kind of sworn off buying physical copies of books, but I will buy hardcovers/first releases of these authors:
George R.R. Martin
Patrick Rothfuss
Brandon Sanderson
Scott Lynch