well, a ROM is a ROM, is it not? It really depends on the skill of the creator. We only have two main chefs, PDAVIET and Itje, and only Itje regularly releases new roms. We're all waiting for his touchit v2 for the wing, which we all expect to filled to the brim with kaiser converted goodness. He's already released it for the herald. Heralds and Wings have different hardware keyboards and, as i understand it, not much else.
Hardware wise, the Wing is quite a solid phone. There have been battery life issues, but thats an issue with all WM phones. Other that, there have been no serious problems. The processor IS a bit slow, but we all overclock to 247 or 273 mhz, so it doesn't really matter.
Aesthetically, the wing/herald is much sexier than the Universal. It's actually quite thin, and I believe was one of HTC's first phones designed for for both aesthetic appeal and functionality.