I don't understand how those on the 50bookchallenge manage it; or at least, I didn't. But this was a very short and easy read courtesy of kharin's library, motivated by an (as yet not particularly planned) holiday in Vienna.
If anything, The Third Man exemplifies the idea that familiarity breeds contempt. It's a good story, but very briefly told, and it does seem to take a long time to get going. A bit like the new Who, where the whole story lasts for only 45 minutes, but most of the action is in the last five. Greene observes in his foreword that this really is the book of the film, and perhaps that's a reason for its levity. I thought I'd read this years ago, but (aside from knowing the film) it didn't jog any memories. An interesting, if not entirely satisfying, alternative to the Le Carré mode of spy writing. (Also on my reading list - somewhere - I want to compare Our Man in Havana with The Tailor of Panama).
As The Fallen Idol (a.k.a. The Basement Room) was new to me, I paid it more attention. It's little more than a short story, much darker than The Third Man in many ways, presenting a child's view of a very adult world. Written in 1935 it's not immediately clear whether it was a period piece at the time; it certainly is now, dealing with the behaviour of domestic servants of an ex-colonial service nature in deepest Belgravia. Adultery, lies, and consequences, without any judgements, presented in a matter-of-fact way that gives them greater melodrama, this definitely read like an outline for a play.