I'm a big fan of discussing the show and how it compares to the books. I'm a guy who hosted a Game of Thrones feast last August, has the calendar, every book (including the latest in hardcover and Kindle version), the soundtrack, etc. So I'm a super fan. That being said, I'm also a critic at heart, though I like to think that Neil Gaiman taught me a thing or two about adaptations when he broke it down during the filming of Stardust.
The pilot episode might be the worst in the entire series. It's not terrible, but it seems more like a race to the finish, to try to get as much dialogue, and as many characters, as possible. Tyrion's the lovable lecher! Ned Stark is Super Honorable! Catelyn Stark doesn't like Jon Snow! Et cetera! The show starts to take off with that final, brutal scene, and while it still encounters some growing pains, the show really finds its footing around the mid-point, and is flying high by the time it reaches its powerful climax. It also does a good job of treating the tenth episode as a denouement to the action that led into it, so you understand where the story is going into the next season while also catching your breath (some - some crazy stuff still happens).
It's not the perfect adaptation, especially in terms of scale. It also coined the phrase "sexposition" as a way to try to soften explanatory scenes with flesh (it was generally unsuccessful as it did so, and also makes one "lady of the evening" pop up in almost every episode, either being referenced to or shown onscreen as much as some major characters, despite being totally made up for the show and having no impact on the story whatsoever), and the show doesn't embrace the very creatures that have captivated fans so much (this appears to be something paid great attention to in season 2).
I think the show is pretty good, and the back half of season 1 is quite excellent. The first half has some problems, but it pretty much starts at the bottom with the pilot (which is still good) and improves over time, and even the early episodes have some amazing scenes (like Arya's dancing master, who is just amazing onscreen). The success and cultural awareness of the show can only stand to improve the attention HBO pays to it, and the source material is not only incredibly rich, but ripe for someone to take the pruning shears to in order to winnow some of the more extraneous elements of the plot while also bringing some "offscreen" elements front and center. This season, for example, an entire plotline of great importance will be "seen" for the first time, since it all happened far away from the narration in the books, and that's exciting for fans of the books to enjoy.
I think the first season is very good overall, and as a guy who never watches more than a few shows at a given time due to unrealistic standards, I can say it's worth your time if you can stomach the blood and skin.