I've seen people post asking about similar ones and the consensus seems to be that they're not as big as they look (its overall 'footprint' is 6.5*2.5 so not much bigger than a normal hutch) so while size-wise it's ok as a permanent base, it doesn't provide enough exercise area.
It also only has a very small inside area, so if you have buns that like to mooch around indoors enjoying the dry, cosy warmth, they haven't got much space to do that - especially if they are also buns that like to have their litter tray indoors. On that basis I wouldn't want to use one as a permanent base either!
