Sammo co-starred in and directed several of Chan's best films during his run of brilliant work in the 1980s, including Wheels on Meals, Dragons Forever, and Heart of a Dragon. The two have had rifts recently; the Hong Kong release of Mr. Nice Guy represented Sammo's comeback after several lean years. (Though that's not the phrase you'd generally use for a man with Sammo's substantial physical presence. He gives himself a brief, very funny role in Mr. Nice Guy; he's the one the bad guys call "fat boy.")
If Mr. Nice Guy does better than other recent Chan films -- as it deserves to -- it should encourage distributors to start mining Sammo's large back catalog of wonderful films, even those without Chan in them.