Any time I want to give the .40 a try, after all, there's a reason it's so popular, right?, I shoot a mag or so through one of the other shooter's guns at my local pistol range, there's always at least one person there with a .40 semiauto, and we all enjoy trying each other's firearms....
(so far, everyone loves my CZ-75B 9mm, even those shooters with "bigger" or "better" guns, the CZ-75B should star in it's own sitcom, "Everybody Loves CZ", would certainly be a lot more watchable than that insipid Raymond crap, dunno about you, but *I* don't even LIKE Raymond....)
But I digress....
Anyway, the times I have shot the .40, it's impressed me with it's nice, heavy projectile, but I don't like the shockwave from the muzzle, or the very "snappy" recoil, it actually seems snappier than the 10mm off which it's based, given a choice between .40 and 10mm, I'd go with a 10mm, which even though it's more powerful, is quicker for me to get back on target
Since I have a 9mm and a .45 ACP, I have no need for a .40, to me, the .40 is a compromise round, the "all season tires" of handgun cartridges, trying to blend "High Speed performance" (9mm) with "Snow and Ice performance" (.45 ACP), and like with all season tires, the .40 tries to be a "Jack of all trades" and ends up being a "Master of None"
It's not a bad round, in fact, it's pretty darned good, I just don't feel the need to own one, even though I could get a lot of spare .40 brass at the range, it's the most common case found scattered on the ground in the pistol hut (some shooters *really* need to clean up after themselves....)