I saw these in the store and thought they looked huge (and wasn't in the market for an iPad a the time). I find the apple pencil really intriguing and am thinking about getting an iPad Pro but really having a hard time with deciding on the size. I do have an Air 2 so know what that size is like, I'm really interested in hearing about others' experiences with using the 12.9 inch and whether you feel that it is too big. I mainly use on the couch or in bed before sleeping. Thanks much!
I was having same kind of hesitation as you are having, at the moment almost iPad Pro 12.9" started taking reservation online. I do digital drawing and edit music, but only iPad I had before that was iPad mini, it compromises my drawing space, but I love its mobility. At that time I was questioning even 9.7" as to go size. First, I thought 12.9" is very huge. But I really wanted to have experience with Apple Pencil since first time I saw their advertisement. I used many pens on iPad mini, didn't like any one of them and gave me frustration, I did try Wacom cintig(old desktop type) and still it wasn't good enough.
So, I hesitated until very last moment and decided to give it a try.
After few months from then, now I love that size. Best size to draw, best size to maximize the benefit from split screen function. Yes it's big when you compare to 9.7", but there are reasons why it was 12.9" and 9.7" wasn't enough size. In my opinion, 12.9" Pro isn't for everybody, 9.7" is good one as well if you need to use it only for browsing websites, reading Ebooks and articles and emails. I'm not a big person so for me the best size to play games and read ebook is still iPad mini though.
Weight, probably bit heavier than 9.7", but I bring it everywhere and cafe and just use it as digital sketchbook. I don't use keyboard, so probably less weight and space in my bag. I love my experience with 12.9", even though I was one of people who wished if the smaller pro was available before 9.7" came out. Now, I understand benefit of 12.9", and it fits my purpose of use.