I was just in TZ for a week with Jason and Maddy. The fishing was poor, but we got some nice GT's up to 35kg. Jason and Maddy where disappointed about the result, there should also be some over 40kg. All of our GT where caught outside Mafia. We also tried Latham, but didn't catch anything worth mention. All of out GT where caught on poppers. The jigging was really bad, just one small doogie.
We also caught, 2 broadbills, 3 sailfish, 1 blackfin marlin, 1 striped marlin, and (of course) lost a few.
Even if the fishing wasn't great, I wouldn't hesitate to go back (maybe next year)