In khakis, or "relaxed fit" jeans, it's just fine. I think it would be uncomfortable in tight jeans, or on horseback or motorcycle. I would also stick to a small pistol or revolver. A 1911A1 will fit, but it's uncomfortable, makes you look like a pervert and carrying there "Cocked and Locked" would make me very very nervous.
So9
I'm carrying using the Smart Carry, a product almost identical to the Thunderwear. I usually forget I'm carrying. It is far more confortable than I ever would have believed had I not tried it. NOBODY knows you're carrying. And now I do carry at all times, instead of only sporadically like before I discovered the Smart Carry. Many US Air Marshalls are cerrying concealed using Smart Carry.
Try it.