Now that you beat me to it:
EtCR had a couple of flaws, starting with a general lack of consistency: If there is no fog, why don't people just flee? -Especially if the game is set in FR, as the intro suggests, why don't move to Waterdeep, when you have to live in Barovia.
Second, the lack of motivation of the main antagonists: Why does Madame Eva help Strahd? Why hasn't Strahd left Castle Ravenloft already? Why do the Vistani first help, and then act against the count... The list is endless...
Third, the lack of logic: So a Knight of the Raven has to spend one night in Castle Ravenloft's cathedral?! - How's that possible with the present situation, or even in general?!
Now, of course, one can fix everything, but it's the purpose of an adventure to give instructions on how to run a scenario, isn't it? - And I measure a good adventure mainly on how clear and free of mistakes such instructions are.
- Back to the original topic, there's really one hope, I think, which is that the campaign fixes itself while running. EtCR is more a scenario, but not a dynamic adventure as I6, and I personally would prefer the later if I had to run a short game. The strength of EtCR lies in the way that you can stretch things, insert more background as you like it - but this fragmentaric setup is also the module's greatest flaw, because it leaves more questions open than it resolves.