Gameplay is similar to Baldur's Gate (click the enemy and your people attack) but without magic. Your heroes (you start with two, but get up to four) do have special attacks, but you don't have a lot of "God Points" (or whatever they're called) to use them with. As they gain levels they gain more special moves, I believe. You can also buy soldiers (archers, swordsman) and creatures (bears, harpies) to aid your heroes, but they die much easier.
I think that if you really enjoy Greek mythology, you'll appreciate the game and seeing all the heroes. Otherwise I would suggest you skip it - gameplay isn't exactly very varied (click to attack! Click to attack!) and the story isn't particularly memorable. For $6 I wouldn't say it's a huge waste, but I think there are better choices in GOG.
Hope this helps!