Certainly would only appeal to a very specific type of person, of which I aparently fit the bill. It's the entirety of Gertrude Bell's letter correspondance, from around 6 years old until the time of her death. Of course her step-mother edited everything down, so it's not literally everything (although you can find the unadbridged versions of letters online).
For me it was extremely intimate reading her letters to her parents - almost voyeuristic to be honest. It changed Bell from a mythical character to a human - the little jokes she slips in, her requests to her mother-in-law for new clothing, goofy recollections of tea parties, etc. And despite the slice-of-life format, the pages are full of legendary historical figures - Lawrence of Arabia, Mark Sykes, Ernest Shackleton, John Philby, Percy Cox, Vita Sackville-West, etc.
Just be warned it is quite long at about 700 pages. The first volume is more interesting - it takes place all over the world. The second half is almost entirely set in Baghdad, where Bell lived out the last part of her life (still interesting though, as it deals with the foundation of Iraq). The last few chapters, where Bell is pushed from politics and slowly descends into depression, are quite heavy at times.
One small critique: when editing the tome Bell's step-mother did some sterilizing in order to conform to the sensibilities of the early 1900s. Bell is know to have had three relationships in her life (one especially fiery one with a married man who died in the first world war). The letters produced from these affairs are fascinating, but they've been entirely removed here (not even any mention of the men). Letters dealing with great loss (e.g. Gertrude's step-brother) and depression (although some hints remain) are also absent (though can be found in the online archives). You can't really blame the step-mother, but it still has the effect of making Bell come across as a little less passionate than she truly was. A new edit someday which includes more of this material would be nice (not that I'm holding my breath...).