The DOS version was certainly more complex, partly due to the use of spells whose effects you had to discover, and enemies that, besides the damage they inflicted, could also affect other aspects of the game, such as destroying equipped items, etc.
While it was a bit frustrating and required many playthroughs to learn, I don't find the Mastertronic version for ZX to be nearly as frustrating. Of course, the snapshots are a big help; you can't beat 18 levels in 5 minutes, but they don't detract from the gameplay experience at all. Plus, they allow you to savor it more thoroughly. ;)