Filipe Furtado’s review published on Letterboxd:
The Mission is set on two different principles. As a dramatic piece it is a loose hangout movie about five dudes learning they really enjoy each other company predicted in a minimalist approach, only essential info (and in a key case not even that), nearly everything that doesn't involve the five guys hanging pushed offscreen. As an action movie it is predicted in the main characters occupation as temporary bodyguards, so everything is stilness, long antecipations and finally bursts of reactive moves. To's camera barely moves and neither does the characters. The mall shooting which is rightly the movie most celebrated setpiece is choreographed through camera placement, archtecture and very posed bodies. Indeed, while it isn't unusual to compare action movies to musicals, The Mission muted stylization (a very self conscious reversal of Hong Kong traditional action) predicted in very rhythmic organization makes it more actual musical-like than the kind of ballet one would get at either a Lau Kar Leung or John Woo picture. I should also add that while I'm sure that it is not actually true it does feel like The Mission soundtrack includes more gun shoot effects than actual dialogue. One of the effects of the juxtaposition of the film drama and its action is how The Mission is a rare gangster movie that is mainly interested in the labor of gangsterism with every element circling around the main characters very skilled execution of their jobs.
Like many Hawks features the emphasis om group dynamics and characters professionalism often suggest a movie about filmmaking itself. It wouldn't be absurd to read The Mission as an allegory about To's funding of Milkyway ans his attempts to turn a decade as very succesful good industry soldier into independence (and To have on occasion mentioned The Mission as his first genuine personal project). It is probably worth pointing out that The Mission was very unusual for action movie shot in semi improvised very tight 12 day schedule with most of the dynamics getting mapped between To and his trusted cast as the shooting went along (that also explain many of the movie heavy omissions and how its last few scenes are more thematic than narrative apt) and this contribute to this overall sense that proccess itself is part of the movie text. It is very much a movie from early Milkyway, very stylish, withdrawn and slick. It is rarely discussed this way but Milkyway played a very similar role for HK action that Peter Chan's UFO did for its comedy/drama, a clear attempt of making a more upscale and respectable version of the industry bread and butter and it is worth mention that while the early Milkyway movies fast become cult items in the west, their local reputation were of being mannered and arty (it was usual to say in the early 00s that To was keeping the company afloat with his very popular Sammi Cheng comedies while doing more personal difficult work in his crime films).
As a last note, from a 2021 perspective it is hard to convey how much The Mission was a breakout movie for To among western cinephiles. Milkyway 1997/1999 slate was all western HK cultists like me were talking around this time, as a new exciting development during the hard early post handover years (which one might call The Young and Dangerous days), but most of the hype were for the movies signed by Wai Ka Fai and Patrick Yau and To's role as the company "creative director" was not as clear for outsiders (that Wai and Yau were young up and coming directors while To was an industry vet who had only one west cult hit with The Heroic Trio probably didn't help). I actually remember To getting described as Milkyway lesser talent in more than one article that come out around this time. In some ways, The Mission felt like To asserting his control over the company creative output although Wai ironic self awareness writing would remain a key component of the company early years (Yau remains disgrunted over the auteurship of Expect the Unexpected and The Longest Nite, although his non post Milkyway career most settle it).