Reading through this thread was a trip, considering Darren Criss's role on Glee and his short stint in How to Succeed. The theater company is still putting on shows in Chicago, but I think they are pretty far from producing something that could be a commercial success to a wider audience.
As a breezy singer-songwriter pop singer he always seemed most at home. Look at his "Human" EP for his solo versions of a few songs he wrote into his musicals later- it's much better than the eventual stage versions.