Not going to lie, one of the most beautiful cities in Europe in my opinion, but I'm also slightly biased obviously. If you're into watching the city itself and you enjoy culture and all that stuff there's plenty to do at an affordable price and it's fairly easy to get around here. Maybe the nightlife and if you're really looking for entertainment it's a bit boring in comparison to the more known options, but if you can live with that it's definitely worth watching and you have the options to go to some of the other capitals around in no time too.
@shamrockgooner Regarding Iceland, you should be looking to go either a bit before or after summer to avoid most of the tourism. Also shammie, as you say, winter is not to recommend if you're going there mainly as a casual tourist. Not only easier to get around, but also bright sky so you can actually see something.