I love Bocas. my wife and I went diving in Bocas for a couple of weeks in December and loved the area so much we ended up buying one of the local dive shops. We'll be moving there in May.
About the diving: Bocas diving is good, not great. The primary negatives are that vis can hover around 40-50 feet after heavy rains (and it rains a lot in Bocas). The other negative is that there are not a lot of big critters. The local indigenous Indians engage in subsistence fishing, so you won't see a lot of big fish. I feel the positives outweigh the negatives: Most of the sites are well protected from high seas so you usually have tiny waves and no current. You will never have a trip cancelled due to bad sea conditions (I've had many dive trips cancelled throughout the Caribbean because of high seas). While there are not a lot of big critters, the reefs are incredibly healthy and there is a huge assortment of tropicals.
Dive operators: I'm biased because I will be an owner/operator come May, but truth be told, there are two excellent dive operators in Bocas, Starfllet Scuba and Bocas Water Sports. both are very inexpensive for Caribbean diving (approximately $50 for a two-tank dive, all gear included). In my opinion, BWS has better boats and dive gear, while Starfleet has a much nicer dive shop and a better web site. Both operators have excellent staffs (I think Freddie, the senior DM at BWS is one of the best DMs I've ever had). While I have a personal interest in BWS, you couldn't go wrong with either operator. I don't know Starfleet's web address, but BWS is Bocaswatersports.com.
Topside: There are dozens of decent places to stay in Bocas, to meet all budgets, ranging from $8/night hostels to Punta Caracol, which is beautiful and goes for almost $300/night. My personal favorite is Lula's Bed and breakfast (lulabb.com). They charge $50/night w/ breakfast and the owners (Bryan and Jana Hudson) are both divers--Jana is an instructor. There are some great and very inexpensive restaurants in town--don't miss Guari-Guari, El Pecado, Om, Cosmic Crab, and Lemon Grass. Lili's is great for lunch. Dinners should run about $30/per couple max, including drinks. If you want very good, cheap local food you can get meals at Chitre' and Don Chichos, where dinners run under $10 for two persons.
One of the things that attracted us to Bocas were the people. Everyone is friendly and helpful. It's a very diverse place, with indiginous Indians, Afro-Caribbeans, Panamanians (of Hispanic decent) and a large number of expats (mostly Brits and Americans), all getting along in harmony. There appears to be little prejudice or animosity between groups. It is truly a melting pot, with virtually no crime.
The topside geography is incredibly beautiful. Beautiful beaches (don't miss Red Frog beach), lush rainforests, classic Carbbean architechture make for an amazing setting for any vacation. Consider taking an all day tour of the Saposo Indian village (approx. $90/person, including lunch) on the mainland. The botanical garden tour on Isla Colon is $10 and is beautiful. Taxis are .50 cents anywhere in town, and water taxis are $1-$2 to the surrounding islands (Carenero, Solarte, Bastiementos).
PM me if you need any further info.