Not that anyone has asked, but I thought I'd try to explain anyway.
About ten years ago I started posting reviews on Amazon, and toiling away, I've now passed 250. Most of them are for books: but a couple of years ago Amazon noticed me and invited me onto their Vine "programme" which offers free stuff for review. Under the auspices of Vine I have reviewed coffee makers, toothbrush heads and even Sugru - and books: it was through Vine that I discovered the possibility of getting review copies, before the book is published.
I still find Amazon reviewing fun: you get fairly prompt feedback on whether anyone likes your review, and they have this addictive thing that gives you a rank, which is probably fairly meaningless but can be a wonderful ego boost.
However, I do worry about Amazon. If they drive the physical bookshops out of business, it will be harder and harder to get the "real" books I prefer. And bookshop browsing is so much fun. So I'm trying to limit what I buy from Amazon and make a point of ordering my books from my local shop.
By the same token I thought I should start putting reviews somewhere apart from (or, if I'm honest, as well as) them. So far I haven't been posting them all here - I'm still getting used to using Blogger. (I know that Google's possibly no better than Amazon, but...)
And just to confuse things I also recently found Goodreads. And my son persuaded me to try Twitter, which turned out to be more bookish than I had expected. Help - I do actually want to carry on reading books, and all this networking uses up the time so efficiently it's actually rather scary.
Also, since you asked, why "Blue Book Balloon"? - a name that possibly makes me sound like a travelling Victorian sideshow.
A few years ago I took a photo of a blue balloon, in a blue sky, as it passed over my wife's church on a Sunday afternoon. It was fairly low and we could hear the gas burners. I used the picture for my profile on various sites, including Twitter when I started that, and I decided to use it for my Twitter name as well.
It is distinctive, and I've got used to it. (Though it caused a little confusion among local balloonists - I was contacted by one who had ridden in the actual balloon).