Thought I would add to this the ability to add a part level to it!
The level is made by Ferplast and is easy to add in with the plastic screws provided I paid around £7. Normally the ladder is a separate item and costs about £2-3. They are available online and I have also found them in Garden and Leisure chains.
The shelf is particularly useful for breaking up the 'open space' as my hamster which occupies it went through a phase of fearing large spaces.
I didn't buy the ladder at first as it takes up more room than the ladder which I already had from my now departed Leon cage!
The biggest advantages I've found over some other cages is the top access and the sturdiness of the doors. However I have found the base stains quite easily.