As I've already mentioned to MartAnimE, episdoe 9 seems to be missing entirely. I didnt' even really notice. Episode 10 was pretty cool though, as it was an extended introduction to "Aqune", the brooding purple-haired young lady who, for some reason not obvious to an English-speaker, works for the evil bug-dudes.
She rawks.

I was going to watch ep 11 this morning with breakfast, but the universe somehow came into alignment and when I was done making breakfast and brewing coffee, it was 10:30 on-the-dot, and the US premiere of the dub was starting on the WB. So I subjected myself to that for nearly an hour.
I fear the dub may affect the "adoption rate" of the usual, typical WB watcher, as it was rather cheesy in spots. That said, there were a couple of rather funny moments that I was impressed with. It's almost as if it's spoofing the typical boy's fighting anime in a few places.
They didn't give the bad guy in episode 2 ("Grashop", I believe), the same level of hilarious "chortle" that the Japanese version had, though. A pity.
At any rate, the hit rate on my blog has astronomically increased, all due to searches on "Spider Riders". Pity I don't have any current information on the post that's ranked so high on Google right now.

At least I have a pointer over here.