The Review mentions that the game has balance issues, and specified that the 'mountain' race has the easiest go of it?
I am uncertain if this is a translation issue? But surely he/she was referring to the 'Warlock' Race? As it is generally agreed that they have the best creature lineup.
I would strongly disagree that this imbalance haunted the series forever after that; HoMM2 shows significantly more balance... until ghosts are introduced in the expansion.
HoMM3 Is a rather well-balanced game; In this case there is only one race that's clearly got a weaker force, and that is the Necropolis. With weaker earlier units and a weaker L7 unit.
HoMM1 is a great game and has a lot of 'charm' you could say, which its sequel somewhat keeps, and seems to degrade slightly into a turn-based 4X game by HoMM3; and the instalments 4 and 5 in the series you start wondering if the developers felt like necromancers who revived the same skeleton a few too many times.
There could probably be a really good debate as to which HoMM is the best;
As to the most fun 'light' adventure/exploration game, i'd go with this one for the original novelty 'high'. Just the fun of sending heroes out and finding all the goodies on the map, and then plotting how best to take out that enemy hero who's making a huge nuisance of itself back home.
EDIT: About CD ROM issues people have, in dosbox I have found that simply mounting an actual cd rom with this seems to work seamlessly; If the game doesn't work there are probably other set-up and configuration tweaks that need to be made. As far as the simulated DOS environment goes, this game is one of the more picky ones.
I'd highly recommended a frontend like "Dos Box Game Launcher" to help you keep configurations for individual games saved and together in one place, so once you have it all set up you need only click on the name and play.