The workmanship is neat, the weight does not burden, using the supplied strap is the take away no problem. The underside is made of artificial leather - so the bag is easy to clean.
I use the bean bag almost exclusively for pictures lying down - ie camera just above the ground. Compared to a tripod you are much more flexible because you can change position much faster and micht must cumbersome fiddling with the tripod. In addition, when you are shy animals so inconspicuous.
The stability is sufficient for the 400 IS without even with less than perfect light normally.
In summary, it must be held - all the best, clear recommendation.