He's certainly more visible in the movie, but I don't see so much of a difference in the basics of his personality. 
 
There are some incidental differences, of course, but when you get down to it, he does what Legolas would do, doesn't he?  I think the main difference has to do with the fact that he looks very much like a 20-some year old kid, and when you read the book he seems older.  But that's a really sticky thing about Elves, they have to look ageless and you'll never find an actor who looks that way. 
 
As to what I thought of Legolas before the movie... *crickets chirp*...  Well, he wasn't much of a rounded out character.  Tolkien even neglected him completely at times (can you say "Pelennor Fields"?)  He didn't have much in the way of his own personal dilemmas or agendas, so I didn't pay much attention to him. 
 
But then again I am a hobbit-fancier, and Elves in general don't interest me much.
		 
		
		
		
		
		
		
			
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				All shall be rather fond of  me and suffer from mild depression.
			  
		
		
		
		
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