The Tanzania coffee character belongs to the Central/East African family of washed (wet-processed) coffees - bright (acidic), and almost aggressively flavorful. Kenya may still produce superior coffee, but Tanzania has pushed ahead and shows many of the same positive qualities of Kenya. Coffee is grown in the North and South and there is good quality potential from both areas.
Peaberries are often sorted out and sold at premiums, but the cup is sometimes tainted and not worth the price. It has become a novelty coffee, and sells well in the US, so many roasters capitulate. Yes, it is a coffee with great potential but shipments arriving in the US do not always express that truly excellent Tanzanian cup.