We had the original one of these years ago.  That one wobbled quite a bit when the cat went up on the top, and the cat wasn't that keen on it.
This one has an extra stiffening bar that keeps it from wobbling too much.
Our cat loves it and almost flies up the levels to the top, but also stops at other levels to look out the windows, or just play.
Assembly:  Simple - just follow the picture directions and make sure you are using the right hardware and there are no issues at all.  All parts fit perfectly without effort and the included screwdriver is sufficient to do the job.
Appearance:  Excellent - just like the photo.  We got Mahogany as our windows/doors are all Mahogany, and this goes very well.  It is a pleasing piece of furniture in our family room.
Our cat really likes the mats on each level.  He lies on them, sharpens his claws on them, and climbs easily between levels.

Pros: Nice appearance, easy assembly, cat loves it.
Cons: None.