There's so many films and so (relatively speaking) little time to see them all ... and you'd not want to watch them all anyone, for there is some genuinely fetid shit out there.
Anyway, Leaving Las Vegas is a flick I'd heard talked about before many times - the Nicolas Cage performance being a common remark related to the movie - and indeed it's a great, if harrowing, performance. For such a dark film, it makes for surprisingly compelling viewing, mainyl due to the strength of the script and the lead performances.
Truly complex characters - in that the viewer feels about them in the same variety of ways the protagonists feel about each other - is the order of the day. You look down on them for their vice-ridden flaws, but you also get swept away by their zest for being when they're high-on-life, and you become saddened by how truly and hopelessly trapped they are by their respective vices - and you find yourself wondering if there is a part of them that wants out, and to what extent.
Compelling, but dark - great script, great performances.