I sometimes find Tristana needs a bit of a rework.

For example, her ultimate.
I find it really hard to nuke someone with that thing,
I think it should have either true damage,
or they should put a physical attack-based ratio on her ult,
because all there is is an AP ratio.

i also find her abilities to cost too much mana, please reduce the cost by 10-15.

Please don't say rework because when I see it I think of changing passives and skill or what they scale with and remodeling a champion. A better word would be buff or nerf.

Her ult should deal AP because all her other skills deal AP. If they made that one skill be physical attack based that would make it even harder to build. Making it hit for true damage would make it a little OP, since It hits hard and knocks an enemy around. (her ult has a 1.5 AP ratio, higher then Sion's)

He passive is completely useless. Id rather it removed and her skills actually deal some mag damage with AD scaling.

I don't think Tristana needs a rework, but her ability cooldowns and costs need to be looked at. They're probably the worst in the game.

No rework! NOOOO!
Her rocket jump needs a bit of a cooldown reduction buff imo. It's 20 seconds. 20 SECONDS! (Then by the time you are like level 13 it'll be at a not-so-bad 10 seconds)
And she gets very low reserves of mana in the firstplace, so she wouldn't be able to spam it nonstop anyway (a buff here might be nice... But, I'd like a cooldown one more).
I really haven't had any issues with the DoT skill or any of the others. Just rocket jump is a pain in the ass. Knowing if you use it to hop over a wall on the way to somewhere it's going to be unusable for a long while.
The refresh on cooldown is a nice idea but, you rarely get to use it to finish people off, since normally in order to do enough damage to kill someone, you have to jump in on them. So a cooldown buff here "might" also help you to use it to finish them off when they are running away.
She is "just" below what a normal ranged carry I think should be. But a few others like Sivir are below her.
I for one, like her passive, and her ult for that matter. x.X

Leave my AP-Tristana alone, pls!

Useless passive?? Attacking physically from a range that makes Caitlyn's long rifle shrivel like a cold day in the locker room and from outside the range of most gap-closers, disables and non-skillshot damage abilities with a massive attack speed steroid is useless, especially when combined with not one but two abilities that can be used to re-establish range if something does get close, one of which is low CD and the other resets on kills/assists?

Huh. News to me.

I always hear people complaining about being able to get hit during her rocket jump escape. Perhaps you could fix that by making her intargetable during her escape.