The story is not very original: As a idiotic knight on the king's court, you have to rescue the kidnapped princess. We had that several times before, as well as comedy.
Eric the Unready is more based on allusions to classics of film and gaming than on an intriguing plot. Serious things (Star Trek) are used as well as other satires are quoted (Monkey Island) or carried on (Monty Python and the Holy Grail) without envy. Of course, that is sometimes done better and sometimes worse. The recognition is high is any case. You will notice the most (and in my opinion best) humor only if you step aside from the normal solution. You can try every silly action you want, the game will recognize almost everything and comment it.
Beside these points of content, the engine is the most fascinating point. Being a direct successor of classical text adventuresis very much text based. There is in fact a (very well) drawn image for each setting, but more specific information are only given by text. According to that there are two ways of controlling the game. There is a mouse interface which includes clicking on graphical objects as well as pure typing. On the short term, the mouse-way may seem easier, but as there is an almost unlimited number of verbs you will get back to the good old typing often.
And there we are, our next point: the parser. You can formulate a command as you like. As long as it does make sense in some way, the program will understand it. The vocabulary is enormous. It may not completely reach Infocom's quality, but the difference is almost non-existant. In spite of the lack of the possibility to try, the puzzles are not very hard. That is on the one hand caused by the fact that they are all logical and on the other hand they are just not on the highest difficulty level. They are quite imaginative, though.
The game is divided into "days". That means that you get to a new place which only consists of few pictures every day. Running aroung endlessly is avoided by that, so that the player can concentrate on the puzzles. A huge advantage, especially compared to most Sierra adventures!
On the whole a true classic! It is a pity that this genious engine has not been published as freeware. Otherwise many games would surely be created with it because it combines complexity and simplicity in a very unique way.