There is a little more action and a lot more Lam Suet in the entry in the PTU franchise. Without spoiling too much, his the vice ridden and somewhat boorish character of Tong finds himself against a loanshark, and being PTU, hijinks ensues.
As with all of the other entries, if you like the series, then you'll like this one, as they seem to be getting better, but if you don't like the films then you'd best stay away. Again, this is not much like PTU proper, but as each entry appears, they carve out a little bit more identity and differentiate themselves.
Good acting, solid writing, and even pacing, make this worth a watch if you find yourself even the least bit interested.