The paceing was about right in the beginning, but it just seemed like they tried to compress everything too much towards the end. I think they could have extended the whole thing by 2 or 3 episodes and still managed to end each one at a good spot and would have ended up with a better end product, but that would have cost significantly more. I hope they keep that in mind for clash of kings. And yeah, Muri Maz Duur wasn't evil enough.
As far as other characters go, my thoughts:
ned stark, Arya stark, Sansa stark, Joffrey lannister (actually a bit more evil than the book even), actually all the lannisters so far (cersi has a different feel than in the book, but it works), the hound, visreys, magister whatshisname in kings landing, most of the nights watch, the kid that played robyn arryn, his mom, Danrys targerian, Drogo (was actually more of a chaacter than in the book) etc.
Caitlin stark seems a bit off from the book to me. I can't place why though. Jon snow, the fight with the dead thingy wasn't even close, so that annoyed me, though the character himself seems pretty close. Littlefinger is significantly different than in the book, but I understand why they changed that a bit. "the mountain" wasn't nearly evil enough. Robert and Renly both needed some work too. Theon Greyjoy just doesn't seem to fit my mental image of how he would react to some of the things that happened so far. Also, the dragons being wyvvern types annoys me.