I have had both negative and positive experiences with teams. On the positive side, if you get to work with people you trust the collaborative spirit can be amazing and drive you to greater achievements in your endeavors. With that being said, if the team has personality conflicts it can be an enormous problem. Backstabbing, lack of trust, exclusion, and arguments can make the working environment unpleasant and unproductive at best.
Most of us on here are teachers and we don't get (or at least I didn't) a lot of training on how to work in teams. So when I've been assigned to teams, it hasn't worked all that well. We are used to being our own bosses and doing things our own way and we often don't buy in to the things that we're being asked to do.
It's been easier being on teams in other jobs. There, I've known that the work we were doing as teams (typically making things) was important and I've known we needed to each do our job to get the final goal accomplished.