Sufyan: THIS. Mafia 1 is by far the worst game in the series.
In my opinion that's bull. I haven't played Mafia 3 yet but Mafia 2 is in my opinion worse than Mafia 1 (and everything I've heard about Mafia 3 suggests that it's even worse than Mafia 2). Anyway, I care as little about the fact that large chunks of the story and characters in Mafia are hugely copied from famous mafia films as I care about the fact that tons of motifs and even specific designs in the Silent Hill series are taken directly from famous and rather obscure films. Just like with the Silent Hill series I feel that Mafia 1's way of reappropriating content from cinema made it something grander and more sophisticated than any of the source materials. A bold claim that cinemaphiles will undoubtedly cringe their teeth over but I stand by it. The developers did a great job of modelling their characters after famous characters from classics like Good Fellas and then brilliantly broke expectations, they made them more real and human than the originals which were merely archetypes. And Mafia 1's character development and writing haven't aged one bit. Well, besides the unnecessary racing episode and a weird break towards the end of the game that I'm not going to go much into to avoid spoiling the game for curious GOGers reading my post - but technically those haven't aged badly, they were crap when the game was new. Anyway, Mafia 1 remains in my opinion one of the best games of all time in this regard and Mafia 2 doesn't even get close.
And sure, the combat mechanics have aged and the difficulty curve is beyond ridiculous, however, the experience I get from combat in Mafia 1 actually remains more exciting and rewarding than the one I had in Mafia 2 with its lackluster cover-based combat with auto recovery which makes things ridiculously easy, ruins the pacing and makes the protagonist appear like an inhuman killing machine that just doesn't fit into the story that requires human life to be remotely fragile.
And as for the music: first off, you have misused the term "diagetic". "Diagetic" means that the audio you hear comes from a source in the game world. That is not the case. GTA's radio is diagetic, the source of the music is your car's radio, in Mafia you usually just hear different songs that are meant to reflect the different districts of this fake Chicago. Secondly, saying that the music isn't good is just crazy. The songs chosen for the game are classics from that era, most of the music is by Django Reinhardt, a friggin' legend who is,
to quote Wikipedia, "regarded as one of the greatest musicians of the twentieth century". Other good chunks of the soundtrack are by
The Mills Brothers and
Louis Prima. Don't get me wrong, their works aren't among my favourite music, but you are kinda making a fool of yourself when you lambaste some of the most influential and famous musicians' compositions and performances of an era like this.
And I don't know how you can possibly say that the licensed music "isn't really part of the mood". The licensed music is not adjusted to the story, no, but it is absolutely adjusted to the era and that's exactly what the sequences where you just drive around the city between missions are about. You just friggin' inhale the zeitgeist, it immensely strengthens the immersion. Not in the "oh, so realistic" sense but that you get a feeling for the time period the game is based in. And personally I like to think that the fact that things can really go to shit while the uplifting music is playing is in itself something pretty amazing. Heck, there are movies where this is done intentionally, from what I recall there actually was a scene in Good Fellas where you see people getting brutally murdered while some rather upbeat rock song from the time period is playing. It suggests that the crazy shit you're seeing is simply part of that era, almost mundane, and it's the moments where you get a different view at your hero, Tommy Angelo. Not the guy with a conscience that he is presented as throughout most of the story but the guy he has chosen to be but pretends he is not: a mobster, member of a self-declared elite that leads a life of luxury and doesn't value the life of others at all. I think the use of this period-music during the sections where the game doesn't put any limitations on your actions, while possibly unintentional, has a brilliant and powerful effect on the experience as a whole.