Eh... Hm....
It's good. Yeah, but it's exactly the same as the other Thing-Things. The graphics are fantastic, there's a significant improvement there, but like, the gameplay is pretty much the same. I don't see what else could be added, and from the last Thing-Thing, not much in terms of actual gameplay was added. I want to see something new in the line up. It may seem hypocritical of me considering I like Madness... but I think you'd see where I'm going with this.
It's not super-interesting. Someone of your capabilities however can really pull something new off. It's the same as the others.
If there's gonna be a Thing-Thing Arena 4, perhaps you can add some new shit to the mix? It'd be a definite improvement considering the foundation you laid for the series.
~S