This is pretty awesome. Only issue I'm having is that it tends to lag on Mac OSX Lion whenever I press the jump button. Also, the music sometimes cuts out all together and doesn't start up again till the next level. But this is just insanely cool!
So far this seems very awesome. I can see a lot of cool fan games coming out using this engine and custom level designer. Should be sweet when we see levels built with the portal mechanic in mind.It's still awesome to see the portal gun in regular Super Mario Bros, but having levels specifically designed to use it should be much better.
My main problem with the game thus far is that, unless u use the level editor to make up your own stuff, the portal gun is nothing but a gimmick, because you can play the game just like the original and ignore the gun completely. Removing fire mario to increase the challenge and perhaps editting the original levels to require the gun to make it past certain stages would've definitely helped.