I played a few games with her just now.
1) She can go to jungle at level 6, with Madreds and a scepter. It works pretty well.
2) Her arrow is slow, and has a pretty small hitbox, it seems. An alert hero can easily dodge it. However, the arrow is good for scouting bushes, since it makes a distinct sound if it hits, like Mundos' cleaver. Are they buddies or something?
3) She can be built as a very good physical DPS. With standart dps items (Infinity, Phantom, bla bla) she hits hard and her burst is very, very good. Her main problem is chasing and getting disabled. Pounce is unreliable, as she just jumps in the direction she is running. Many, many things can go wrong with this. I would have preffered her to have the old flash mechanics(where you point and pounce).
4) Her trap is...meh. Teemos' shrooms laugh at it from the skies. It's good for scouting, but nothing more. It's very hard to pull a trapkill off: you would have to setup a trap (in bush?), make an enemy follow you, hit him with an arrow, change shape, pounce, use your w, your e, your q, change form again, hit with javelin. This is a pretty sick combo, but in practice it can go wrong on so many levels.
5) She gets targetted and focus fired a lot. A bit of an Udyr mentality there, I think.
6) Her passive is meh, very situational. It might help to close the gap on an enemy if you jump out of the bushes. However, one slow, one stun, and your chase is over. Which makes me say again: SHE HAS NO ****ING CC!!!!
7) Her heal is fairly alright. She is no Soraka, but I managed to keep my team mates alive in skirmishes more often than not. It's pretty great.
I think number 6 is her biggest problem. As a DPS, she has no innate CC, which is why other carries will still be favored: Jax, Trynd, Ashe, and so on. I don't know why, out of 6 abilities, none of it got a slow or a stun, or a chance to stun, or anything!