My cat (7 years old, 9lb) will not go on this because of how wobbly it is, and it shakes a lot. I have the poles fitted so, I'm not sure what more I can do. 

Improvements: 
make it less wobbly (a screw up post would be better vs the spring post used in this cat tower) 
add grips on the bottom of the base
Make the bed ring larger
The top shelf of the cat tower is awkward to reach and dismount from.
the bottom pole could have been a scratch post too.  

Pros: 
would be more ideal for a kitten or younger cat
price was good for what it is