There isn't much to say, other than this is the latest entry in the PTU based Tactical Unit series. The short version is, if you like one, you'll like the others.
The long version is that this is solidly acted, but maybe just a little subdued. The actors know their characters, and by this point, so do the regular viewers, so there are no discrepancies. All of the actors are in character, and the dialog follows suit. At this point, it really is just the main Trio of Simon Yam, Maggie Siu, and Lam Suet driving everything, which isn't a bad thing at all.
The story is good, if a little light, but PTU and Milkyway Productions in general, are straight forward, and become more about camera work, acting, and pacing, than story. Needless to say, everything technically is solid. Like the other entries, music is good, but almost non-existent.
All said and done, it is a good watch, and like most Johnnie To related productions, mostly review-proof.