TL;DR: Amazingly convenient but, as an American, the unit had an extremely strong odor coming from the bathroom (not sewage) and the towels smelled like mildew.
In terms of convenience, this place can't be beat. It's located right by an MRT station (underground subway) that has 2 lines running by it. It's a couple blocks from great shopping and great food.
In terms of everything else, the unit was pretty clean and looks exactly like the photos. The lofted area and bathroom ceiling is pretty low though, so anyone above 5' 10" would probably have an issue.
The biggest issues I had was with the overwhelming odor coming from bathroom pipes, which dissipated to barely bearable with the window left open 24/7, and the towels that smelled like mildew.
The odor wasn't sewage and the best I can describe it is nauseatingly sweet cigarettes that thickened the air. We nearly cancelled the first night we were there. The host and his cleaning crew couldn't smell it though, so I think they're just used to it. My grandfather's place is nearby and his bathroom has a much more subtle version of this, so I think it's something with Taipei.
The towels smells like mildew -- like the just washed, but not completely clean kind of mildew. I understand that this kind of thing sometimes happens, but the frustrating part was that I asked the host for new towels and he told me to just use the smaller hand towels in the unit, which also smelled Iike mildew. I was so over it by that point that I didn't bother asking him for new ones. Based on the way he told us to use Lysol from under the sink to cover up the scent -- I asked for a candle AFTER he asked us what we needed, but he essentially refused by telling us to use the Lysol in the unit -- I figured asking wouldn't result in anything. The host is super responsive, just not the most helpful in addressing any actual issues we had.