FOR FLAT THINGS in engineering, and for tamps, coins, fabrics, prints etc, the high quality lens (and very large too, compared with a jewellers loupe) makes this the best. It also has a fold-out measuring scale and so can be used in place of the traditional 'linen prover'.
FOR THE PARTIALLY-SIGHTED this is about the most powerful you will get. With increased power comes a smaller field of view, i.e. you will only be able to read one word at a time. But for those that are very nearly blind, this may well be the only magnifier that works.