It looks like a nice set up - although I would suggest putting a lot more substrate in - so it is a centimetre or two below the edge of the cage base and maybe pile it up in the middle a bit. Although that takes up a fair bit of substrate, it doesn't use any more in the long run because the bottom half stays dry usually (especially if they use a potty). I use Erin's cage cleaning method which works really well for our hammy who got very stressed by cage cleans and it means you basically recycle about 2/3 of the substrate each time.
Aside from that I would suggest maybe adjust the long ladders slightly - he might feel a bit insecure up there on them. The one on the right - if you lower the front end down to the house level it would help. I actually think those long ladders are best just used as ladders - to get from one place to another, rather than hanging toys. I had one and our hammy didn't like it - it made him nervous because it moved!
But mainly I'd suggest putting a lot more substrate in
And maybe scatter feeding half his usual food amount (put the other half in the bowl as usual. They like moving substrate around and he might even dig some tunnels, but they also like it for burying food in and piling up into mountains