Apart from it not being ready production-ready, I find the syntax confusing and overly engineered. Perhaps I'm just dense. However, as a programmer with 5+ years of experience, it feels rather off that I can't look at some of the Opa code and understand what is happening.

Haskell providers a lower barrier of entry.

That being said, it's different. I wish them the best as the more options available to a programmer, the better.