playing nidalee mid i found many issues.

• nidalee has problems killing tanks.
• nidalee has issue waveclearing safely.
• nidalee uses too much mana (50 or more per spell) with almost no base mana (300 - 1000)
• it's hard to land your Q.
• in late game you are almost useless.

you can fix some problems.

• aganist tanks you can avoid the assassin build and play bruiser or support.
• to waveclear in early game you can incerease your attack speed with your runes. You are going to lose some adaptive force.
• you can try to not use too many abilities in early game. and buy a mana item when you recall.
• in late you can splitpush or heal your teammates and throw your Q.

nidalee has some good points

• you will probably kill your opponent after you land your Q in early and mid game.
• you are strong if you roam.
• can steal objectives.

this champ doesn't have many good points but if you shutdown your opponent you will win anyway.
if you roam you can help other lanes you are useless in late anyway, so why won't you help your teammates win? But you should remember that is hard to waveclear with nidalee.