It is a text based game, which means that the environment is described and what you type is carried out by the character. If you have read the Hitchhikers guide to the galaxy, it helps but all in all you will feel the surge of satisfaction after completing a task, especially the notoriously tricky ones.
You may think that the game may be limited in its interactivity levels, but trust me, the developers have gone to great lengths in making sure that everything you can 'see' in the environment has some use or atleast it can be picked up for later use. It is always a great feeling when you discover something completely useless but insanely funny, I remember once when I was at my house ( inside the game)and there was a telephone and I typed 'Call home' , and the game replied : What are you, E.T. ?
Go ahead and play it. It is really funny and a top notch text game.
Ps. Tip : Make sure you save the game frequently.
Pick up stuff, coz you will need it later.
Dont get frustrated if you die a lot.
For the more difficult parts you might want to consult the solution ( google it )
I can help in the Babel Fish puzzle, I'm a pro in it
Please reply and tell me whether or not you liked it.
Also, if you want to play offline, go to www.sadena.com/hh/hgttg.zip
)... and the ceiling is collapsing all over me (after 19 moves)... better luck next life! 
