Beck is overall an entertaining animation by Harold Sakuishi.
As everyone has felt and will feel, the story progresses on the slow side. This should not be an issue.
There are an array of diverse characters to enjoy throughout the series and much of the character development is done quite well. Or well enough so that you know the role they are suppose to play in the plot.
Some of the animation is a little on the skimpy side, but in animation you can play it off as to give the series atmosphere the art was rendered so (but if you read through the original work you can tell the animators for this anime were slacking or you'd question budgeting as the art work in some places drop big in quality). It is nice to see a real place get animated into this work (I.E CBGBs,-I was sad when they shut down-, other venues).
Guitar enthusiast, might love or hate the guitars that are show cased in this animation, I for one loved the idea that they used Gretsch (I love this company, sad they were bought out by fender)guitars instead of just sticking with Fenders and Gibsons. Harold Sakuishi also incorporates a "legendary" guitar or a well known guitar in the blues world, into the storyline which is entertaining in itself.
Music is great. I am a big fan of the Beat Crusaders and they did the most of the major musical work in Beck. The Husking Bees vocalist was used as the main singer, which wasn't too bad. I would venture to say that all the music used are quite "catchy." This is a great story told through a great medium.
Also, like one of the other reviewers noted, this anime will make you want to learn the guitar. I agree 100%.