This book in the Hitchhiker Guide series is a bit unlike the rest. It revolves almost exclusively around Arthur and involves him falling in love.
This book is pretty witty, but not as much as the rest, and there is less action, since love is more of a sweet thing, and in this case a bit less exciting than improbability drives, creatures out for revenge and Krikket wars. Also, this book takes place mostly on earth, which may account for it being a tad bit more dull, because as everyone knows, earth is pretty lame.
The end is quite interesting, and it takes some unexpected turns and brings in some characters one would not expect to see again.
I know I said this book was a bit more dull than the rest, and a bit less witty, but if you take into account how interesting and witty the other books are, then you will realize that this one is definitely worth a read as well.