Is Oslo a nice city to visit?

Yes.

its bit late if we tell you anything bad as you are already going!

It is indeed lovely but can be a bit of a shock to the pocket for people from our part of the world, especially if you like a drink...

I would recomend it highly, for me it is the Nordic city with the most attractions.

Oslo is nice, for a city with 600' people it's got the feeling of a small town. Nice, friendly, clean, lots of parks and water..... Expensive, though, but if you avoid the worst tourist traps it's not too bad. Don't buy the 'Oslo card', get the day pass for local transport instead.
Make sure you visit the viking ships - for sheer beauty!!! And don't miss Vigelandsparken - free.
Enjoy Oslo!

Oslo is a very nice city with a ton of culture in it to visit. Definitely a city worth visiting, just don't stay for too long. It is small and easily covered in just a couple days (three days max, visiting most worthwhile museums / attractions), and if you stay any longer you'll find yourself either bored or broke.

The Viking Ships Museum for me house some of the most beautiful things ever made by man, and is certainly a 'must see' for me.

I have just returned from Norway and visited Oslo twice. I had a great time both times. There are a multitude of museums to satisfy most any taste and I would recommend a visit to Vigeland Park. Pick a hotel close to the Sentrum and you won't have any problems getting around. The Tourist Information staff was very helpful.

Personally, I didn't like Oslo that much. There are nice areas and not so nice areas (around Oslo S train station). I found it to be extremely expensive and I too got fed up of being harassed by beggars. I am however a little biased because I visited Bergen and Trondheim beforehand and found these cities to be far nicer in comparison. I'm sure Oslo is fine for a short city break but take plenty of cash!