You have been told right that it is a low port curb.
It wouldn't be my first choice in bits to use but it's a long way from horrible. It looks to me like stainless steel (judging from the obvious lack of rust) and while that is not an ideal metal for a bit, it is much better than aluminum or nickel plating.
As far as curbs go, it is a relatively mild one; short shanks, low port, etc. However, due to it having stationary shanks, I would not use it on any horse that didn't neck rein perfectly.
Not a great bit but if your horses neck rein well, it might be worth keeping as a backup.