The Serbs were awarded the role of Bad Guy during the wars that broke up Yugoslavia after Tito's death. With leaders like Slobodan Milošević, Radovan Karadžić and Ratko Mladić, you can kind of see why.
NATO bombed Belgrade – without UN approval – in 1990. Visiting the city today you wouldn't see much damage as they've done a lot of development since, but there are still traces. One fairly big building near the centre in still a bombed-out carcass. Presumably they left it as a reminder of darker days.
The city itself is interesting, though not beautiful in my opinion. In that way it reminds me a little of Nantes: you don't go there for the architecture, but for the atmosphere.
The street I stayed on is in a pedestrian zone, well supplied with cafés, bars and restaurants. The prices are great value by western European standards: a nice three-course meal, with aperitif, mineral water and two glasses of wine for around €25. And there are many cheaper options. A coffee and a cognac on the way home at midnight cost me €5.
And they're really nice people now that we've put manners on them!