Just as both
Darkfire and
Daemian stated:
Working in a group motivates you and pushes you forward.
But I would say that developing in a group might have many negatives (just like working alone).
Darkfire mentioned disagreement or scheduling, which are very valid points. I myself would also add the potentially tense relationships between members or simply lack of organization. Though too much organization is also bad.
An interesting "rule of thumb" so to speak might be something like this:
A developer is most likely to succeed in a group development when he feel completely confident in developing custom stories by himself and has some finished projects.
Though I wouldn't quote myself on this one, since it is highly individual and while some people might be naturally good as a team player, some might "lone-wolf" their projects for years.
As for my preference:
I prefer working in a small group of 2-3 members, where I can easily bounce my ideas off of someone and be sure that the person understands.
Hell, I met really amazing people in some groups. My current
best friend is from the last group I've worked in.
- - -
I just think that whatever you choose, you should love it. There are too many projects that are TBD or past release date with no download that whatever you choose, bite a very small chunk.
I would much rather see 10 average custom stories worth of 10 hours of average fun, then just 1 super-amazing 30 min. custom story.
Jesus, sorry for this Rant.