Easy to put together, my 11lb yorkie fits perfectly inside with room to turn around lay down, etc. My dog is 18 and gets tired on long walks which is why I got this. I didn’t want to leave him home, instead when he gets tired I put him in this with a fuzzy blanket.  My only complaints are I wish the stroller was taller and the front wheel worked better. I’m 5’9” and it’s a little short for me when I’m walking, the other complaint is the front wheel gets stuck in an awkward position when you’re turning. It’s happened more than once. Ive even double checked that we put it together and we did. So just be prepared that it could be annoying if you use this a lot.