I've held one but didn't have a chance to fire it. I saw the paper target the owner was shooting at and its quite accurate.. at least he was. Definitely a nitch firearm but can see the fun in them. From what I've read the biggest drawback for people is the limited 10-round magazines and the unreliable aftermarket 15-round mags. Most people would prefer a 20-30 round factory mag for a carbine weapon.
As for Hi-Point in general a lot of people can't get over the price thinking they are cheap guns. Well they are. That said, awhile back I bought a new Hi-Point .45acp handgun. While its pot metal slide is cheap and the darn thing weights slightly under a full ton
it has about 800 rounds through it and its never had a single issue! It fires every time I pull the trigger and its quite accurate as well. It can also be used as a club weapon due to its size and weight if bullets were to run out.
I ran across another use one for under 100$ with a few extra mags. It fired poorly and could hardly stay on paper.. Likely why I got it for they price I paid for it. I sent it into Hi-Point, got it back fairly quickly (with a new free mag to boot!) and it shot perfectly. Sold it later but kept the mags for the one I still had.
If you shoot 9mm handguns and your looking for a budget carbine I can't say I've read much bad about them. From what I've been told and read they are mostly reliable and the bad ones are replaced or repaired by the manufacturer quickly. Their lifetime warranty is great. It also transfers to the current owner so regardless of new or used Hi-Point stands behind their firearms.