We have just returned from three weeks in Montenegro, and this map was literally falling apart by the time we left - even so, our tour reps wanted to keep and mend it, because it was by far the best they'd seen.
It was useful when we went on excursions, and caught local buses. But it really came into its own when we rented a car for four days to really explore the country. All roads, railways, rivers, etc. are clearly marked and everything is colour coded. There are symbols for every feature you could possibly think of, too, although it's never so 'crowded' as to be confusing, and the key to symbols is clearly listed.
All in all, I would really recommend this to anyone who really wants to get to know Montenegro, rather than just staying put at or near their resort.