Heroes of the Modern World is a mixed bag. On one hand, it's basically d20 modern for Pathfinder, on the other it has some rather grating issues.
For one, there are times when the typesetting fails (as evidenced in the armor section where the entry for heavy armor, heading and all, jumps into where the body paragraph for a piece of medium armor is, ignoring the correct column it should be in), and numerous typos plague the work, which always grates with me for much the same reasons that posters not hung up straight do (namely I'm somewhat obsessive). Also, it's basically d20 modern, so take all my d20 gripes and add in the fact that it's not terribly original (though if you do want to play in a modern real-world setting, it's not that easy to be original), and it's been done before. Also, having DC's of 25 on things players will probably be doing fairly early on is a bad idea; it's the same reason some modern systems only go to level 10 compared to the d20 system's standard 20, or even eschew levels for a point buy system. It's almost impossible to succeed some rolls until level 5 or so, and then a lot of stuff becomes very easy.
However, when the typing's done right, and the layout's good, I like the writing. The typesetting doesn't glare like some products, and it's pretty solid. The talent trait feat everything meshes together well, though sometimes there's an obvious break in balance in some of the things. The archetype system instead of classes just seems like an attempt to write everything in one table rather than just writing out a progression table for each class type. Admittedly, it's not different, but it just means another cross-reference every time I look at the "archetype", rather than just referring to a table for each.
Above average in some ways, below average in others, a dab of polish could make Heroes of the Modern World a must-get product, but as is it's interesting, but only for those who really show an interest and don't want to take the time to write down stats and rules for modern things themselves.
[3 of 5 Stars!]