In general, comedy ages badly. Shakespeare, for example, is painfully unfunny, and so are many of the old stand ups and sitcoms. Wodehouse, however, is still genuinely and deeply funny. And the humour is so wonderfully warm and kind and all-embracing. There really is nothing like it. I think it's harder to be funny than to be witty (Oscar Wilde is witty, but Wodehouse is funny). However, it's even harder to be funny without being nasty or crude. Wodehouse pulls it off effortlessly. Reading him is like "swimming in champagne," as someone said.
I just don't know how to over-praise him. Marian Keyes said that Wodehouse created a world, and it's so true. Very few writers have managed that (I suppose Dickens and Jane Austen would be the exceptions). It's a world without evil and cruelty and death, though. Douglas Adams said Wodehouse managed what Milton could not – he re-created paradise.
But the humour is wrapped up in the language. You can't disentangle them. He creates his beautiful, sunlit world out of language. Take away his spellbinding language, and you're left with a load of selfish rich people behaving idiotically. If you don't love language, you won't love Wodehouse. It's as simple as that. Frankly, I don't even think of him as a novelist. He didn't write prose. He wrote beautiful prose poetry. If you want your son to cultivate a love of language, he's your man.
He's best read out loud, however. Wodehouse was just made for audiobook (so was Evelyn Waugh). Stephen Fry reads him superbly. I constantly read him out loud. (Though I say so myself, I do a pretty good Jeeves.) He's better than Prozac.