I've only used stretch fabric for my Blue Beetle suit, which is entirely made of lycra, and personally, I've only had good experiences throughout the construction. There were mistakes, but they were unfortunately more related to my not paying attention rather than the unease of stretchy fabric...
The armour like shoulder/knee pads were done plushie-style, and I'll tell you that it takes a lot of stuffing to make stretchy fabric look full.
Also, like sooyong pointed out, it leaves a lot of room for anatomical error. I made the hips of my BB suit a little small, but...because its stretchy, you wouldn't know if you didn't. That part is nice when I wear it with no hood or binder and I can just be female Blur Beetle, and my chest doesn't feel crushed or constricted, because the fabric just stretches.
So...I like it
"I would like to be the air that inhabits you for a moment only. I would like to be that unnoticed and that necessary." -Margaret Atwood