Is this worth watching? I was tired of KF Panda halfway thur KFP2

It will meet all your bad expectations. Sadly, it is everything you said and you will be disappointed half way through, if not before.
For some reason, I thought I really liked the first two. But my memory fooled me, I didn't rate the first two high at all, even though my memory made me believe so. So I went in thinking this would be great - also due to all these glowing reviews on imdb... What a mistake I made - this movie sucked bad.

If you found the other two just 'meh,' then maybe the third won't do it too well for ya. It picks up on some themes brought up in the second movie and once again focuses on Po trying to understand more about himself.
Personally, I find the movies very engaging and really admire the direction they take with Po's journey. There are a few parts where I sort of wince, but they aren't distracting enough to take me out of the moment. These films are really amazing in showing the character fighting through both external and internal struggles to unlock their true potentials.

For this third one I was completely glued to my seat and when it seemed to be wrapping up, I felt shocked because I hadn't noticed how quickly the time went. There were a few parts I sort of rolled my eyes at, but the story and the animation itself was more than enough to hold my attention. Unless one is really invested in Po's journey, then I don't see this next installment doing anything for them.