After scrapping and being on UK scrappers for years, I recently took part in the Newbie circle journal, which was just pages, rather than the whole book.
I have loved it! And I have learned so much! (thank you fellow flyers!).I will say if you are thinking of dipping your toe in....do it!

[U]Good Things!
It makes you think! What ARE your favourite Lyrics/clothes/sweets
You learn new things.(I now have flaps on everything!)
You see beautiful work
You try new styles.
You learn a little bit about fellow scrappers....good for the nosey.
It gives you a time scale and reason to use your inks!

possible bad things
It costs more than you think to post things...not so bad for pages, may be crippling for a big book. Make allowances!
You are tempted to buy more things...(as in, Ive seen a stamp that is perfect for my 'music' page....)
You may get scrappers block...other peoples pages are so lovely, I dont want to spoil their book.
Things (like life) happen...in the course of a long journal there will be holidays, illnesses, which will cut down your time.

Would I do it again??? Yep...already planning it!