Hi, the diving around Pemba is nice, when you know where to dive. The problem they have there is that all the good diving is somewhere in the middle of the Island on the western side.
Unfortunately with Swahili divers leaving from Chake Chake and opened a new resort in the northern area there is noone left to do the diving in the mentioned area. Swahili Divers now offer diving along all the north west coast but you have several hours of driving to get to the better places and they cost much more than the normal dive trips.
Than there is only one other operator in the south, Fundo Lagoon, and for the dive sites in the center of the Island they are also too far away but the south has also 2 great sites to dive at. Fundu Lagoon is not a budget place with 320$ a night. So the diving offered in the north is not nice due to dynamite fishing which can be seen clearly on the reefs.
Unfortunatelly there's dynamite damage around the island as well as bleach damages from the 1998 El Nino; but still plenty of healthy reef to dive - if you know where to go.
I don't agree the only good diving is on the middle part of the western side (are you talking about Mesali Island?). There's lots of equally great diving to the north as well as to the far south. The eastern side also has some good diving, allthough very different and not as pretty as the eastern side.
Personally, I found the drift diving to the north of the island to be some of the most rewarding 'flying' over healthy coral "mountins" (no dynamite damage there), loads of reef fish and bigger stuff (3 spieces of barracuda in big schools, jack schools, wahoo, tuna, turtles...).
There's a new place in the far south now, run by Manta Reef Lodge owners. The name escapes me. Certainly not budget.
/c