Learn Turkish: Şimdilerde o adam ne kadar da başkalaştı, nasıl da gençleşti! - How much that man has transformed nowadays, how he has grown younger!

Even though ne kadar (how much) and nasıl (how) are question words, adding the particle da turns them into exclamatory intensifiers. Here, they aren't asking for information; they emphasize the speaker's surprise at the change, translating perfectly to the exclamatory "How much..." and "How..." in English.

What is the difference between şimdi and şimdilerde?

Şimdi simply means "now" or "right now". By adding the plural suffix -ler and the locative -de, we get şimdilerde, which translates to "nowadays," "these days," or "lately." It refers to a broader current period rather than a specific moment in time.

How are the verbs başkalaştı and gençleşti formed?

Both verbs use the suffix -laş / -leş, which attaches to adjectives or nouns to mean "to become [root]". Başka means "other" or "different", so başkalaşmak means "to become different" (to transform). Genç means "young", so gençleşmek means "to become young" (to grow younger).

Why use the simple past tense (-tı / -ti) for these verbs if the sentence is talking about "nowadays"?

In Turkish, verbs describing a change of state (like growing younger or transforming) often take the definite past tense (-dı/di/tı/ti) to show that the change has already taken place and is an established fact. The speaker is observing the completed result of that change "nowadays".