Well, from what I've figured about the module I6: Ravenloft and the 3.5 edition module (having DMed the 3.5 and read through the 1st edition one), if you try to analyze them on the cannon timeline, I'm pretty sure that all that happens during the transition stages before the other domains come, and therefore Strahd is much much younger a vampyre and less powerful. I mean, they classify him as as a CR 15 monster in the EtCR for Christsake! Of course, in that timeline, by necessity they have to be non-canon, because if Strahd dies before anything else can happen the DPs just lost their first Darklord. EtCR has to be noncannon, tho, 'cause they have Madam Eva be a hag. And that's just stupid.
But yeah, that module was one of the first ones I ran PnP, and I got my first PC kill from it. (Freakin Rangers not being able to pass Will saves...)
It had some interesting things... but, I mean, seriously. The Daystar? Interesting, but I mean come on.
I do have to admit, though, the KotR is a good class.