Heard of it? I actually own two copies! Of course, that was totally by a gift-giving accident, but anyway...
Of all of his works, Tea-Time is my least favourite. However, since he is my favourite author, it is still one of my fav books.
That book in particular gave me difficulty in figuring out what actually happpened when I got to the end. It was a bit obscure and, in my opinion, didn't actually explain (in plain words) why certain things were happening. Of course, after I re-read, and re-re-read, it I got more of the jist of things. Then, after talking on some forum boards about it, I REALLY started to get it. Then I read it again and REALLY, REALLY got it.
I would definitely have read Dirk Gently's Holistic Detective Agency first, but if you didn't know, don't go back now, just read it afterwards.
It is an awesome book...