It's all about the mood. Those simple graphics magically teleport you to the lazy summer day in a tropical island. You can feel a breeze from the ocean shaking the palm trees. Fantastic stuff. It's unpolished though, so if you rotate the camera wrong, you can look at the bookshelf during dialogues. I hope they'll fix that and let you control camera more.
Yes, the lack of music is retarded, but to truly enjoy Mafia nowadays you need to mod it a bit anyway. Modding scene is brilliant and sets like Optimised Mafia will help you to get the best experience from the game. You'll patch the soundtrack in along the way. Just please don't put Kanye West in it, ok?