This is awesome. The only change I would make would be move the nacelle pylons aft leaving the nacelles themselves in the same place relative to the saucer and secondary hull. That would make the ship scream Excelsior to me.
I agree with that... The pylons are a wee too far forward... But whatever.
Let me preface this with my disdain for the ubber size of the nu enterprise... That said. MadMan's ship really reflects the scale of the nuExcelsiour in relation to the nuenterprise, and it really works here.
By abondoning the idea of "using" an almost exact copy of the original Excelsior saucer (like they did with the TMP enterprise), it's allowed him to make the larger scale work more effectively as far as I'm concerned.
This ship, to me, is a truely in-spirit of the original Excelsior. Taking the shapes and specific details, twisting them around into something quite graceful looking. And more balanced dare I say (because I get kicked in the balls for bashing the nuprise) then the nuenterprise.
One thing I was really taken aback by was the warp nacelles. The cowling is a truly clever interpretation of the original's... Wrapping them around like that really is a good idea. My only suggestion would be to tone down the thickness of those cowlings. Make them more subtle looking- almost more fragile looking.
Anyway dude. This is a freaking awesome looking ship. I'm really looking forward to seeing it completed.