Great little secret.
I really love this city. Slovenes are especially nice and very enthusiastic on helping you. There's a lot of history and there's graffiti everywhere but it looks really good, the city is by no means dirty. It's very clean and very hip. It's a young city. There's a lot of music and nightlife and people are always hanging out. Go to Metelkova. It might look a little sketchy but noway, they're the nicest people. Slovenes serve American sized portions so be careful as you might order too much food.
Insider Tip:In America music shows get crazy at midnight in Ljubljana they seem to end at 12 on Friday and a little earlier on Saturday. The time they shows are going on though are not wasted. They have lots of fun and I had a blast. I love this city but it's not like a huge city. I think you only need about 2 days unless you want to get deeper.