Another Question for the Movie Answer Man

I've been writing to Roger Ebert through the Sun-Times web site for years and years, and read his "Questions for the Movie Answer Man" for years and years, and not ONCE has he answered my question.

So I figured why waste the brilliance of my missives? To that end, I present my latest question to the Movie Answer Man in its entirety:

M. Ebert, Something you said in your review of "Criminal" reminded me of your favourable review of "Matchstick Men," which you gave four stars and I purchased on DVD as a "blind buy" based on your recommendation (also because I generally have an affection for con and heist movies). I was a little annoyed with you at the time because very quickly into the film I could see the obvious "twist" and was hoping throughout the rest of the film that I was wrong and that the con-within-a-con wasn't so facile. If the movie gave clues that led us to believe there was something amiss, but ended showing that everything really was as it seemed, *that* would have been a coup. Now in your "Criminal" review you say that "Matchstick Men" worked because of the intense acting (which I loved) apart from (or despite, perhaps) the con. Isn't it infuriating, though, when a film with so much potential, like "Criminal" or "Matchstick Men," goes wrong in the third act? Your positive review is like someone taking a European rail journey, having the train derail at the station killing most of the passengers, but then saying that you had a really enjoyable trip "despite the ending."