My first handgun was a Hi-point .380. It was ungodly ugly, heavy as a brick, and way too big for the caliber. However, EVERYTIME I pulled the trigger, it went BANG! Would it serve well as a concealed weapon? Only if you have no other option and you have a big purse or pocket to stuff it in. Would it be useful as a home-defense weapon? If you have no other option, sure it would. Would it be fun at the range? Certainly more fun than pointing your finger at a piece of paper and yelling BANG.
However, you asked specifically about the carbines, so let me give you my impression of them. I fired a 9mm belonging to a THR member (Bowlcut) a few times. It is spot on accurate out to the range you'd want to use a 9mm carbine. Put a red dot on it and you won't have any problems with accuracy. Recoil is next to nothing. The biggest problem is like mentioned earlier, you will want to shave the areas around the seams. They will irritate you to no end. Also, they need to release a higher capacity mag now that the ban is gone. That or they should have made the carbines and the pistols to take the same mags, preferably both.
Everyone I've talked to who has fired one has seemingly been equally impressed with them. They are an inexpensive, fun, reliable weapon.
Frank