This is a superb microscope considering it's under £10. Unbelievable really.
I use it to examine the scratch patterns on blades and it is perfect for the job. I used to work in a cytology lab, so I have some experience with optics and for this price the pocket microscope is incredible. Don't be fooled by toy microscopes claiming to have 1000x magnification - you can't achieve that without expensive optics and the specimen has to be properly prepared in order to view it at that magnification. The 1000x toy microscopes just give you a faint blob of light with some vague fuzz where the specimen is supposed to be. Their objective lenses are tiny and they have very low light-gathering capability.
The 40x magnification on the pocket microscope is a real 40x with a bright, crisp image. The Natural History Museum did the right thing - they went for high quality optics at lower magnification.
It's a great educational toy, for sure (try examining a bank note with it), but it's also completely fit for purpose for anywhere where you need good magnification. Worth having around even if you don't have kids.
At this price, you simply can't go wrong. For once you will get more than what you paid for.