If you have read the book, you will notice that Ms. Rand does spend a lot of time on a character's internal monologue or thought process; sometimes this can make the book a little dull and drawn-out and clearly cannot translate to a movie screen very well. Yes, there are voice-over monologues from movies like Sin City or Watchmen but not too terribly much. There weren't any voice-over monologues in this movie...well, only a little, but nothing distracting. However, as a negative this means that you can't really get a deep feel for the characters--you simply have to pick them up as they are in the movie, if you know nothing about them at all. Noty hasn't read the book but did a pretty good job at picking up details about the characters, I must admit.
The dialog does seem a little...I don't know quite how to phrase it..."dated" or "flat", perhaps. In the defense of the scriptwriters and actors, though, the movie was shot in only 26 days (isn't that almost some sort of record?) so they didn't have a whole lot of time for retakes.
The other negative is that there are certain characters and sections of the book that had to be completely thrown out. Richard Halley, the formerly-famous composer who mysteriously disappeared along with scientists and industrialists, isn't even mentioned (he might have been a quick blurb in a newspaper article or TV screen but I couldn't take in all the extraneous information on the first viewing only). Ivy Stearns, who goes into detail about how she and her brothers ran 20th Century Motors, was reduced to only two or three lines of dialogue. We don't get any history of Eddie Willers, who grew up with the Taggarts, and who is extremely concerned about the state of the world. We also don't see any of his lunches in the company cafeteria with the rail employee who seems to have a bright mind.
Finally, the only other negative is one that the producers and directors encountered with Lord of the Rings--time. It would not have been possible to film everything from the opening of the novel to Ellis Wyatt destroying his oil fields in anything less than 6 hours. This forces some of the dialog and action to move at a pretty quick pace, much faster than the novel.
In short, devotees of the novel--and the people who are die-hard Rand devotees are more purist about their book than even the most die-hard Tolkein fan about LOTR--are going to hate the movie. They are probably also going to dislike the acting choices because they might not look how the characters are "supposed" to look. Whatever.
Now for the positives. It was actually a very enjoyable movie, both for me (I've read it twice) and Noty (who has never read it). All the essential elements have been captured--the world is going to hell in a handbasket (and no one can stop it), people who have the personality of being leaders and innovators are disappearing without a trace, and the people who want to "spread the wealth" are ushering in their ultimate vision of how the world is "supposed" to be. The script found a way to keep Taggart as a rail company--they are using double-decker high-speed rail lines for shipping (easy to do when gasoline is $37.50/gallon

The way the story is presented will give audiences who might not have read the novel the desire to go buy a copy and read it, thus introducing more people to Objectivism and capitalism done in the proper way (not like a robber baron, but responsibly with respect towards other men).
Dagny is presented as she is supposed to be--not an air-headed female who giggles and hangs on her man's arm. No, she is smart, dedicated, competent, and capable. She is also compassionate, which sometimes loses itself in the book. I've never seen the actress they cast (I don't think anyone has) but she did a really good job. I also like the guy they got for Hank Rearden--he has the right look and presents the right personality for that character.
The outdoor shots taken in Colorado are amazing in their natural beauty.
Yes, the movie had a really low budget and they shot it in less than a month. However, I think what they were able to make is a really good start that captures the spirit of the novel. It will be interesting to see the ticket sales numbers after this weekend. What I suspect is that a) the producers will make a profit on the movie and b) the production budget for Part II will be increased, allowing them to make that part even better than this one was.
Finally, the best positive about this movie--it isn't a Hollywood movie. Yay! The critics hate it, which is generally a good sign.

In short, go see this movie.
P.S. Noty is my wife; that is short for "notabarbiegirl", her online name.