I got a few minis of this in the Christmas Beauty Blender sets I bought last year. This is some concentrated stuff. Now if you think you just roll your wet BB in it and with a little lathering in your hands all the staining comes out that's not how it goes especially if you wear a long wearing foundation or you're a deeper skintone so your foundation is darker. I'm a Mac NC25 my foundation doesn't immediately come out.
I do have to really lather it up and rub it a few times to get the foundation out, but I have found this solid gets out the stains much easier than regular brush cleaner and even a bit easier than the liquid Beauty Blender Cleanser. If I have washed my BB and I have some staining left on the sponge and it's dried on and I use it again and use the BB solid and lots of effort it can get out the old stains leftover from the previous wash. I can't comment on how this works for brushes because this is pricey I save this for my BB, but based on how my BB liquid cleanser cleaned my brushes in the past this would easily remove any makeup out of my brushes. I would recommend this for anyone who wears long wearing foundation or really doesn't like stains on their BB.
I got my Beauty Blender Solid in a pack with my BB sponge as a gift, and I'm so glad I did! It has a really lovely soft lavender scent and it really cleans both my BB and brushes well. I've only used it a couple of times so I can't speak to it's longevity however as it's a little on the small side I'm not too sure how long it will last? I've definitely made a dent in it after washing all my brushes only once (around 30 of them), though to be fair they were very dirty which could have something to do with it.