Where do "mobster" films fit into crime films, or are they a separate category? Heat was great, and getting Pacino and DeNiro on screen together was a fantastic feat. Although my favorite Crime film (outside the mafia subgenre) would be Reservoir Dogs.
Where crime films are concerned I tend to be more of a fan of the old noir classics. Bogart, Cagney, all those guys. For me crime movies were perfected by The Maltese Falcon.
Personally I thought Heat had its moments, but was hamstrung by its three hour length, which could have been made more manageable had all the scenes devoted to the male protagonists' problems with their wives/girlfriends been sliced. Those scenes are also a problem in that literally every single one of the movie's roles for women depicts them as having nothing going on in their lives but constantly fretting over/being pissed off at their men. I won't say the movie is sexist, but its treatment of women is so condescending it might as well have had none of them in it, as all their scenes drag the pacing to a complete halt.
The wives/girlfriend scenes were integral to the film. They gave the characters another dimension as well as showing their understanding of other people. Ultimately the actions of all the protagonists had impacts far beyond themselves and this needed to be shown - the lives they led, and in the end lost because of what they did, good or bad. This film could have been longer if Mann wanted but it was a triumph of editing to get it to that length!
I dunno, I didn't really think those scenes offered much narrative depth beyond the obvious fact these guys were pissing off/alienating their S.O.'s. Mann could have shorn a good 35 minutes off the running time and more than adequately communicated that these men were making life-impacting bad decisions. Have a look at the 1954 French crime drama Touchez pas au grisbi, which runs 96 minutes, for a example of a tight movie where the focus is on the relationships between the characters, and the sacrifices they make based on those relationships.
But hey, I'm glad you thought Heat was effective. As with every movie, your mileage may vary.
I agree overall, although I think the film could have sustained all the domestic scenes it did had the female characters had depth beyond "frustrated significant other." The only bit that I thought really worked well out of all these scenes was the part near the end, where Ashley Judd gives her husband Val Kilmer that one subtle hand signal, warning him away from the trap that she's the bait for. A great moment of subtlety. Conversely, I never bought into the DeNiro/Amy Brenneman relationship from the outset.