I won't claim to be a huge fan of the Heroes of Might and Magic series. However, this installment is by far the best in the series, and with the two expansions this is a great value ($9.99!).
The gameplay will be adored by fans of exploration and rich worlds. This is similar to the fallout series. However, I find the plot, graphics, and user interface FAR superrior. In particular, the party system is far better than that of Fallout.
As always, turn based combat adds an element of tactics you don't see as often in RPGs as we'd like to. This is far different from hack and slash titles like Dungeon Siege and Diblo, but still more tactical than even combat based RPGs like Fable.
Any RPG fan looking for something a little different should seriously consider this game. The layers this game has makes it enjoyable on many levels. As GOG says on their page for this game, "This is a must have for every Might and Magic series fan! "