If you are asking for how Jackson portrayed Elves and Hobbits in the movies I think these are things he did fairly well on (we'll say he passed
). I'm thinking from an overall perspective, there are some characters that I did not like the portrayal of and wish they were changed...
For the Elves it was mostly just Legolas and Elrond. I just don't like how Jackson shows Legolas as being this superhuman (or do I mean superelf?) that does cool slides and is "The most awesomest bst boeman like EVER." I can understand heightening Legolas' role a bit (for example the cave troll in Moria), but Jackson just takes it too far with the shield and trunk slides, and the horse mounting.
Elrond I just didn't like his portrayal at all throughout the entire movies. Rivendell is supposed to be the last homely house west of the Misty Mountains and Elrond didn't make it appear too homely. I just got like he wanted Aragorn to fail so Arwen wouldn't marry him and he hated everyone except his elves.
For Hobbits I can't go into how badly Frodo was portrayed. Frodo is a character that shows much bravery throughout the books and he's reduced to a stumbling, bumbling fool that constantly rolls his eyes. But, I did like all the other hobbits (I loved Ian Holm as Bilbo and Sean Astin as Sam).