なかなか

With a positive word after it, なかなか means "quite", "pretty": better than you expected. It goes in front of an adjective or a verb, and before a noun it takes の.

With a negative verb

With a negative verb, なかなか means the opposite kind of thing: "not easily", "just won't". Something you want or expect keeps not happening. The rest of the sentence decides which meaning you get.

This use has its own entry, なかなか〜～ない.

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Praise with なかなか sounds like someone passing judgement: "not bad at all". It suits a friend's work, your own, or a teacher talking about a student. Said to a teacher or a boss about their own work, it sounds condescending, and とても is the safe choice.