First of all, I go there often but it's not for me. My wife was born in Finland which is the closest counrty to Sweden and H&M is like their name for everyday 'closet'.
It's a decent sized shop. The men section actually has some cool stuff. They have the European style slim fits and also the comfy shirts and sweats. The colors are modern, not too colorful, and the jackets are pretty warm for the price. I don't shop there recently but I know because I used to go to another H&M before I movrd to Charlotte when I was younger.
The girls section is just full of all types of clothes. Personally I think it's for twenties and early thirties only but it could work for anyone who needs aomething to go out for dinner.
Last, the price is just awesome.