I don’t write in quite the same way Matt seems to: my approach is much more “spew out as many words as possible for half an hour, then edit and refine until everything makes sense”. The bean bag comes in handy primarily whilst refining.
Unfortunately, I had to buy a set of four bean bags, rather than just one. As I’d predicted before the bags arrived, my go-to writing bean bag is the blue one. My second favourite colour bag is red. I find the green and yellow to look reasonably unpleasant: I don’t really want them sitting on my desk.
Throwing a bean bag up to just below the ceiling is an extremely fun game to play, which takes my mind off what I’m currently writing about. After a minute or so playing like this, I often find myself having “eureka!” moments, whereby I realise exactly which word I was looking for. This is why I bought them; they delivered what I was expecting. Your mileage may vary.
The bean bags fit in my hand well and have surprisingly similar proportions to an iPhone 5: if you want a size guide, the bean bags are approximately 10cm wide by 15.5cm long. The iPhone 5 is about 5.75cm wide and 12.5cm long. The smell of the bean bags wasn’t pleasant initially, but I’ve had my blue bag out in the open for less than a week so far and the smell is starting to fade. I imagine any odd, artificial smells will completely disappear within a month.
The texture of the beans is firmer than I expected. To give a rough impression of what each bean feels like, imagine a dodecahedron made from tough plastic, about a quarter the size of a pea. The beans are not round; when squeezed tightly and played with in my fingers, “clicks” can be heard as the beans pop past each other. When talking about the entire bag though, the individual texture of one bean becomes largely irrelevant. Together the bag feels about half-full of beans, giving it a pleasant weight and texture. Squeezing the bag as tightly as possible doesn’t result in an uncomfortable feeling and I’m not the slightest bit worried about the bag splitting.