Hi!
I have one - it's very handy. Yes it attaches with velcro. I use it for those bits and pieces - a lint roller, glass cleaner, some kitchen roll, etc. I think it was worth it - I'd already spec'd my options and then argued a price for the whole car from there, so it's hard to say whether I actually spent £25 on it. At the time I had no idea what it was - it just sounded like a good idea!
--Rich