I spent a few months in Sihanoukville. The road trip from PP is quite hairy - Mad Max stuff.
Sihanoukville is okay. Just okay. The downtown is an eyesore, and the beaches, other than Otres, bleh.
Loads of low-end 'travelers', beer and dope heads, dealers and purse snatchers.
You're a gal - best to keep in a small group. I can think of dozens of better beach towns in SEA (Vietnam, Philippines, Thailand), but Sihanoukville (Otres) is about the best Cambodia has to offer.