As others have mentioned, study groups can be beneficial. The best method, IMHO, is to have a schedule where everyone does practice tests and you discuss them. This allows you to see what issues you may have missed, and it encourages you to study at a consistent pace which is conducive to learning the law.However, choose your study partners wisely! So many study groups devolve into "parties" rather than studying. Also, note that Wally's right: be wary of discussing irrelevant materials such as sub-sub-points or crazy policy tangents.
I could have typed this post myself. This was exactly how my study group functioned. There was a core group of 2 or 3 of us, and occasionally we had 4 or 5 people. Our core group did very well and we all ended up pretty highly ranked.