As a solo female I was pleasantly surprised by the way I was treated. I've been to other Arab countries but with the exception of Oman and Iran (who were even better), as a woman was well treated.
I got the whistles and the "bonjours" every now and then but if I ignored them nobody bothered me. I was alos guided around for free in the Kasbah by a great university student who lived there. I noticed very few tourists but I highly recommend Algiers and Algieria to anyone. I had a fantastic time.