Well, I liked it. I have to say it did stray a fair bit from the books, but in my opinion that was necessary simply to make it into movie format. I mean, the extended versions were pushing the 4 hour mark and there's only so much a person can be expected to watch in one sitting. There were lots of bits that would have explained the store more, but that were dropped just to make it shorter.
Aside from that, Gandalf was pretty much how I'd imagined him reading the books. I thought Sir Ian Mckallen did a really good job with him.