Upon superficial examination, the Clever Cycles "Stealth Pantaloons" look like regular trousers in every way. They are made of a lightweight wool and have a classic, straight cut to them that tapers slightly towards the ankles.
In addition to the elasticised feature, there is something about the fit of the "Stealth Pantaloons" that allows for unconstrained movement. I can mount a diamond frame while wearing without feeling any pulling at the seams. Same with pedaling or pretty much any motion. This is not typical of form-fitting women's trousers.
Another cycling-specific feature is the flat seam construction. The "Stealth Pantaloons" do not have a gusseted crotch. However, the seams are flat and do not cut into my "soft tissue" (crotch-related problems on a roadbike are an ongoing theme for me!) when I lean forward on the saddle. I have not gone on long rides with these yet, but I can usually feel seams right away once I am on the saddle, whereas these I cannot feel.
Update 18 April, 2011: After 4 months of wearing the pantaloons, I have a few things to add to the review. On the positive side, the manufacturer's claim regarding stain resistance has held true so far: I have spilled coffee, tomato juice, various soups and other items on this garment, and there are no visible stains. There is no visible wear on the pants so far despite my frequently donning them. I cannot feel the flat seams at the crotch on a roadbike even on long rides. On the downside, the pants have stretched out and become somewhat baggy, while I prefer a slender fit. I might try shrinking them intentionally in the wash.