The wonder we feel in modern usage is entirely to do with approval: we are pleased or gratified by what we see, even to the point of wanting to emulate it. This sense had developed by Shakespeare's time, but the first use of this word, when it arrived in English from French in the early 16th century, lacked the personal element. It meant simply "amazement, astonishment, wonder". The context often makes this clear - as when Rosencrantz says to Hamlet: "your behaviour hath struck her into amazement and admiration" (Hamlet, III.ii.334). As the subsequent closet scene suggests, it is not admiration in the modern sense that Gertrude feels.
Where we have to be careful is when there is no immediate context to help us out, and where the modern sense could apply, as when Innogen says to Iachimo: "What makes your admiration?" (Cymbeline, I.vii.38), or Ferdinand describes Miranda as "the top of admiration" (The Tempest, III.i.38). And when the King tells Lafew to "Bring in the admiration" (All's Well That Ends Well, II.i.88) -namely Helena - he means, perhaps a little sarcastically, "marvel" or "phenomenon".