A few of my girlfriends and I went to Belize for a weeklong vacation and decided to spend the last four nights in San Pedro. If you're on a budget, and don't expect the Ritz Carlton for the small price you pay then Pedro's will be fine for you. We sprang for the deluxe rooms, and we're glad we did. (Us women folk like the non-shared showers...) The staff was friendly and was always willing to give you advice.
San Pedro is a really tight knit community, and it really showed. I decided that I wanted to go diving on short notice and Peter just got on the phone with the dive shop and they sent a boat down to the nearest pier (3 blocks away at the belize yacht club) and picked me up.
The best part about Pedro's is the people that you meet. A true party place, the bar was well stocked with Jagger, beer, and fun people. Poker, beer pong, pizza, and great people more than make up for the budget accommodations. As long as you remember that you get what you pay for, Pedro's is a great place to stay on your trip to San Pedro!