I just bought 3 more of these (already had 1) because they are an awesome price and excellent quality. Very sturdy, the sisal posts last, (6 cats who all used them) and it looks great. My cats are fat and huge so I just didn't bother installing the tunnel, they'd just get stuck in it. No big deal, gives more room for stretching and laying.
Was very good for the first little bit, my cat loved using the top platform. However it became wobbly and the top platform came off and will not screw back on. My cat still enjoys the bottom platform.
Just got this built like 5 minutes ago and already my 4 month old kitten is loving swatting at the mouse dangle. Was extremely easy to assemble and as a bonus fits in with my living room decor.