I've been playing this game for a good week now, solo. I've been offered several times (in-game or by other means) to join groups but refuse to trust anybody that I don't know in real life. From my experience, it's neat at first and very fun. However the longer you survive and the better geared you become puts you in a constant state of paranoia - the fear of losing all your gear which I think is amplified because you have nobody to back you up, or help you. I've basically been shooting other players on site (within a range I believe is adequate to kill at without firing too many rounds off) or avoiding them completely. From all reports grouping up is a much funner option minus the trust issues if they aren't very close to you. Soloing is fun for a while, but once the paranoia starts to set in, it makes enjoying it much harder.