Everything goes better in a group: writing, speaking and yes, also arguing, unfortunately. In the best case, everybody learns and the whole is greater than the sum. In the worst case, however, your paper turns out to be chaotic, your presentation a mess and the peer evaluation a snake pit.
How do you make sure that everybody contributes and that your assignment is good and finished in time? You will find tips here about group dynamics, writing and presenting in a group and also peer evaluation.