The reason I'm asking this question is because I occasionally get this offer from time to time. The only official ones that I participated in were Sprite TV 2 & 3, but ever since I finished Sprite TV 3, I decided to distance myself from collabs mainly because of an incident that occurred the day after that flash was uploaded where I personally felt humiliated over a post I made about supporting sprite movies. I ended up feeding the trolls unintentionally and got a nasty backlash from the haters. From that point on I only participated in collabs, but in a limited way through voice acting (mainly in Osuka's flashes).
Now, back to the general topic of collabs. They can be good, they can be bad, they can be controversial, or they could simply be a waste of people's time. Collabs are good in one way because of the interaction between authors and animators in order to make something fun and worth watching and maybe even make something really epic out of a team effort. On the other hand, there will be the occasional collab where it starts off with high expectations and ends up failing miserably, sometimes on purpose if this was started by a troll.
Now lets talk about the authors in a collab. we have the users who are known and praised for their own work, the novice authors who like to lend a hand and the users who are sort of "leeches" who just want to take advantage of someone else's talent just to win an award and because they don't either have the time nor motivation to develop a solo project (or just suck at it), thus working only on collabs.
I'm not saying that everyone acts this way. There truly are people who are interested in working with other talented authors, but for another purpose. In my case, I got a particular offer to join a collab so that I could guide and help out the new animators who are interested in flash and the collab leader even went as far as saying "it would be awesome to work with one of the best!" Though I found this encouraging, I had to turn it down because my semester at the Uni got heavy this year.
As for me participating in a future collab, well, we'll see what happens. I'm choosing my side-projects carefully from now on and I don't want the same thing to happen to me all over again.
Overall, when it comes to collabs, participate at your own risk because you never know what could happen. Just sayin...
nanocon
well i think that they are good if the right people do it i have seen some really amazing ones and some that are crap on steroids but thats always the risk you take so yeah since you asked you should consider it and if the trolls be haten WHO THE HELL CARES WHAT THEY SAY there probubly componsating for small penesis be piking on ya besides if your having fun doing a collab thats all that truly matters right