I've had my Eglu Cube since last July, and it's okay so far in the sun.   We move the chickens into the garage for the winter, so the cube was cold but sheltered.  The color hasn't faded or anything.
Mine also has a wider crack on one side than the other, but it seem to function just fine.   It's been that way every since we assembled it.  
My chickens (5 bantams, 3 full size) also had problems with the wide spacing of the rungs.   Especially at night when they're going in, because someone's always at the top of the ramp pecking everybody else who tries to come up.   I cut a piece of 1" grid plastic fencing and cable-tied it over the rungs, so they can step wherever they like.   This helps a lot.
One thing I really wish it had that's missing - a divider between the two sides of the nestbox.  They say it's big enough for two hens at once, but given that my chickens don't like to be that close to each other when laying, it's functionally one box.  I tried putting up a curtain between them, which helps a little.   But since there's only one door, usually the second hen won't enter the box while it's occupied on one side.