There's a slow start with the first chapter--Benson's humour is entirely character-based, so you needs must meet the character before the jokes can begin--but once they begin, they don't let up.
Luckily (because you'll want more, more more after this book) there are others in the series. This first book sets the pattern: wealthy, intellectually-pretentious, English housewife Lucia wants to be thought of as the exemplar of good/interesting taste, and will stop at nothing to achieve her goal. The characters are all frightfully interested in the most trivial things, and it's screamingly funny.
If you like Benson, try Beverley Nichols (oh, and do read the other two funniest novels ever written, mentioned above--you owe it to yourself.)
Note: a 3 star ranking from me is actually pretty good; I reserve 4 stars for tremendously good works, and 5 only for the rare few that are or ought to be classic; unfortunately most books published are 2 or less.
But such an excursion is necessary, for though Benson brings us so much delight, we must also pay heed when he taps us on the shoulder with a grave rejoinder.
Optimists all, however, will keep in mind that these are the works of a youthful, headstrong Benson, and it was the mellowing years that begat the exquisite decoction Luciaphils exist on. One would hope all headstrong young authors would improve so.