(Sixth edition reviewed.) Why do guidebook authors tend to be so anonymous, when (in theory) they need to have been on the ground to experience each location, visit each 'sight' and at least skim the hotels? This is the pleasure of the Bradt guide: often written in the first person one gets a real sense that Briggs has been there, done that, and had a good chat in Swahili with the locals on the way (although he admits that he didn't update the lastest edition himself).
Sure, there are times when his opinions may be misguided but that doesn't stop this being a useful and entertaining guide. I probably wouldn't count on it as your only one, having travelled to Tanzania with two guidebooks - Footprint and Bradt, both chosen since they were published in mid-2009 and have reasonable reviews here on Amazon - there's just a sense that things in this guide aren't *quite* as reliable any more. These two are a good complement to each other, and Brigg's passion and knowledge are terrific.
Probably the biggest thing that counts against the Bradt guide is its size, or rather its weight: I'd say it's almost a kilo (but don't have scales to hand to prove that), which is going to make a dent in your hand luggage.