The Armour is 22cm wide, the Eclipse is 24cm. The Armour is actually wider than I though, so its not as much of a difference as I thought.
The Eclipse is as deep as the Armour according to the measurements on the Thermaltake site, but I imagine the flappy bits on the front make up 2-3 cm of that
Apart from the front it is all alluminium, and its really light for the size of it, Much lighter than my old Standard ATX sized steel case. Whilst also being much stronger.
According to the thermaltake site the Armour is made of steel, which would explain its huge weight of nearly 16kg. The Eclipse weighs only 7 (according to a competitor, couldn't see it anywhere else)
The Akasa Amber fans go very nicely with the case, but you will find opinions on fans varies a lot, the Ambers are the only branded 120mm fans I have used so can't really give you a comparison. You'll find lots of mentions in the Overclocking and Cooling section though.
The only thing I don't love about this case is the plastic front, but its decent quality plastic and will take a lot of punishment, so no need to worry about a scratch on the front of you precious system
The only thing I particularly like about the armour is the fact that the whole front is 5.25 drives which means you can arrange things nicely, but having that means some great features of the Eclipse wouldn't be possible. Or certainly not as easy.