I have to agree with the screw the courses suggestion at least on a partial level. For my case, such courses have been a waste since I am looking to score in the top percentile. All instructors I've had scored lower than what I wanted (and what I eventually scored). For the LSATs I am aiming for a 172+. The majority of students in the course are looking to pull a 165 and the instructors rarely score over 173 (aside from Testakers instructors who have to at least score a 173). So are you looking for any law school or Harvard Law? A course isn't going to help you but may weigh you down. I remember my Kaplan GRE teacher (I have an MFA) telling the class to skip the hard ones. F%CK that I wanted a perfect score and ended up studying on my own and demanding a refund since the course was geared toward achieving a good score not a perfect one. So its up to you but none of the instructors, though all presumably intelligent are rocket scientists either (if they were they wouldnt be teaching now would they?). Sorry to sound jaded or cynical but the truth is if you dont have gumption nothing will help you and if you do have gumption you dont need a course you need to drill your head off.
I think the benefit of taking a class has a lot to do with motivation and how you learn (much less to do with raw intelligence). I studied my ass off for the Sept LSAT, entirely on my own. What I didn't realize then that I see now looking back, is that I was not efficient or as effective as I could have been. It is easy to delude yourself when you have no one but yourself to be accountable to for your study habits and honesty with where you're at. A course instructor can serve as a coach, if that's all you need, and it's worth it.
I started out with the PowerScore Bibles and developed a good foundation from them. But it is just harder to learn from a book in the same way interacting with a live expert. I've heard that Testmasters is the absolute best, but they weren't offering any courses when I needed them (and don't offer an online option). So I ended up taking Atlas LSAT's online course. They have some great techniques, and it is very beneficial to see alternative approaches to the same problem types I had previously tackled using the PS methods. I think even more important though, is the live interaction with a live teacher.
If you think you don't need a prep class and can get to where you want to be by simply taking 57 prep tests, you're probably right. But if you are strongly considering taking a course, just do it. Do your homework up front to make sure you don't pick a bad course (ahem, Kaplan), and do your homework during the course. It will pay off.