Great review! This cage looks exactly the same as the Pets at Home Pick'n'mix cage (is it the same!?) and I agree it is a terrible cage, I have my Campbell dwarf (she is old and struggles to walk around so she is in a smaller cage) in the pick'n'mix cage and It took 1 hour to actually just get the cage up and put the tunnels together! It was so annoying and once it was put together I was so disappointed with it, the base and the level was flimsy, the water bottle leaked and the bars where a great size but in the corners they would bend so a hamster could easily get out! (Luckily my hamster has never tryed to escape as she's too weak but a young Syrian could easily escape!)
Last but not least it is WAY too small to house a hamster, it would be ok for a temperaray hamster cage or for a young or elderly hamster like pip but its only 64 cm when the minimum size is 80cm....
The size would be ok IF attached to another cage like you said!
Thank you for doing this review hopefully people will see this before buying this cage!!!