The Garni Hotel Fortuna is a small, family run hotel (the family actually lives there!), where as a guest you're treated on the first place as a GUEST. It's a great experience for a very reasonable price. It's not in the center of Belgrade (keep that in mind so you're not disappointed upon arrival, it's up to half an hour driving depending on traffic) but all other advantages really make up for that. The restaurant is of good quality - both our pizza and risotto were tasty and also the breakfast (always included) was of a good quality.
I confused dates during the booking proces, as a result of which my booking was for 1 day too early. One phone call to the hotel sorted it all out, they rescued me - while as per the terms and conditions (non-refundable, non-changeable) they did not need to agree on that.
We will for sure be visiting Belgrade again, as this time we were just in transit, and I don't need to think a second about where we will sleep. Thank you Bojan & family, thank you Sergio (hopefully I write your names correct) for all, and see you again in future!