I think one can look at the entire series more sympathetically if it's read back-to-back rather than as serialised. I read eps 1-7 two weeks ago in the space of five days and then ep 8 as it came out. As a result I didn't really spend that much time theorising over the whodunnits. Indeed by the end I felt most of eps1-4 didn't matter as much (that is to say I felt a resolution wasn't what r07 was aiming at). If you've been mulling this over for four years and were expecting a complete solution I can understand why you'd be annoyed (even though I don't agree).
On a more humdrum note:
One particular flaw I found with the construction of Ep8 itself was the final battle with bern/erika. Whilst the library side of the battle was relatively interesting, if slightly drawn out, the golden land side was horribly boring, especially in the first half. Endless descriptions of a fake argument nearly sent me to sleep. In the entire battle nothing really happened and *was* as planned, simply a stalling tactic. That's all very well, but did r07 have to do devote so much time to it? I think a bit more fleshing out of the tea party and the ???? would have been a lot more productive.
Also I rather felt that zts' lastendconductor was rather wasted on that fight scene.
re the would you read another WTC game? Definitely. However as AuraTwilight said, it's essentially his magnum opus, so I'm not entirely sure where he'd go from here. Also I imagine that everyone would be rather more on the look out for hijinks
EDIT: Damn, Will Wright read my mind.