One difference from Verilog/VHDL is that Cx will handle state machines for procedural code automatically. Bluespec has a similar facility. Also like Bluespec, it makes the clock implicit which makes a lot of code less noisy.
I personally didn't find the semantics to be unreasonably complicated, but the type system is very much based on Haskell's so if you're not used to that there'll be more of a learning curve.