Zork II directly continues the adventure of Zork I. You explore an underground land looking for adventure, treasure, and a way out.
The primary weakness, as in Zork I, is a lack of story. There is little, if any, plot or characterisation. The setting, the dungeon itself, has no thematic unity. It is just a collection of locations to contain the challenges. This is not as bad as it sounds, since the whimsical nature of the game invites a bit of silliness.
The challenges are very difficult. They are well crafted, and generally have reasonable solutions. What are lacking are sufficient clues to solve them without resorting to resurrection: you must die, or enter into a no-win position, to acquire the knowledge to solve the puzzles. The latter is a serious failing, since you might play a large part of the game before discovering that you can't continue because of something you did long ago. It may not even be clear exactly what it was that you did wrong or when you did it.
There's fun to be had, but you must be careful to save often. This is a game for serious adventurers only.
Solution by me.