B. M. Everett
The biggest improvement, the thing that really made the game easier to handle, and less annoying is the automap. The game saves every square you walk upon no more wondering where you are. There is no longer a need for the location spell, I don't even know why they put it in the game(I guess if you don't have the automap or are in a magical dungeon).
The biggest improvement, visually, is animation. Almost everything you encounter is animated. The torches on the walls, every friend or foe, and then some. Since we're discussing the visual effect I'd also like to add that there is a sky and it looks different from night to day. :)
To gain the most experience, exploring the dragon cave in the north eastern region is very helpful. Just walking on a few squares will get you dozens of encounters with the toughest monsters known as dragons. Each battle with a dragon will give you a lot of experience and cash.
A little advice for beginners: Don't always use the same party members. Each class has to complete a quest, with only members of that class int the party. So have at least three of each type of character at at least level 20.
Level 40-50 should be enough to complete the game.