Jidi is right, make sure the volume is set to max, I was quite annoyed until I realized that

a) volume is at 50% from box
b) volume buttons swap when you rotate phone
c) volume is per-app and global, nice but tricky.

All that said, I expected it to bake my ears bleed since the speaker is quite nice. Earpiece is average, sounds almost identical to my old N80 and 7610 (and every other Nokia I had).

At least on N80 I could set it to speaker and hold the phone sideways. I look like an idiot but it's guaranteed to deliver. N900 can't really be used like that.