Reply to is it worth it

The 90D.
resolution increases from 24 to 32mp
11fps with faster buffer clearing and memory support for UHS-II. (You can shoot more bursts)
video resolution increases to 4k
double the battery life
a sealed body (splash and dust proof, a benefit when shooting in inclement weather conditions.)
two years of technical improvements (processor, firmware, memory)

Physically a little larger and heavier
price (your going from an entry level consumer grade body to a more advanced (but still) consumer grade body.

To me, if you are doing a lot of wildlife, it might be worth the investment, but if you are only shooting occasionally, may be better to wait for the price to come down as mirrorless becomes more prominent. I suggest you try renting a 90D to see if you like it first.