The downsides: super sharp edges make it uncomfortable to rest on oneself, the power socket is flimsy and the charger easily damaged, awful drivers for the Broadcom WiFi chip.
I tend to give laptops a rough treatment lugging them around (my ThinkPad was continually damaged and had bits shattered off it on a regular basis). My last laptop was a Toughbook which bravely survived years though a few screws came out of it. The Samsung has done very well and the only damage is to the charger and the screen getting bright patches from being squashed in transit.
The SSD is very fast, maybe faster than the Intel X25M I had before, and I'm generally pleased with it. I use Ubuntu without major issues.
That said, I find the OP a bit unclear. If you need a computer that runs Mac OSX, your choices are clear, though fairly limited. The discussion in that case is about what form-factor you prefer (ultra-mobile, portable, desktop).
If you don't care about operating system, but are looking for a computer with a similar design aesthetic and form factor, there are several choices. The Samsung Series 9 is the closest match, in my opinion, for being metal, thin, light, and lacking a optical drive. With an optical drive, I would suggest the Toshiba Portege (R835) or so, which runs Ubuntu well.