This is not a cgae I have personally, but I always recommend that all tubes are left off from any cage untill the hamster is tame. It is very difficult to get a hold of your hamster when they keep running off up the tubes where they know that you cant get to them.
Also they are not good for your hamster to sleep in, they do get very smelly and damp with condensation and is not very hyginic or healthy for the hamster at all. Agian, if this is happening, I always suggested removing the tubes for 2 weeks, let your hamster establish a nest elsewhere in the cage and then replace the tubes again. Hamsters like to feel safe and secure and so usually like to squeeze themselves in to as small a space as possible! Its certainly not unusual.
The hamster haven is a good cage though and is a really good size. We are always on the look out for the 'perfect' cage, but one doesnt seem to exist! Also different things suit different people and different hamsters. I am sure that your little hammy will be very happy in his cage.
Welcome to the forum