Overall 4/5: our stay wasn't perfect, but we would be happy to stay again if we're in the area.
There's a lot to love about this apartment. The obvious highlight is the gigantic (240 cm x 200 cm) window giving a 7th floor view down onto the buildings and mountains of southeast Taipei. The view makes the nook in front of this window an incredible place to work, eat, or hang out. Equally great is the kitchen, with its U-shaped countertop affording a huge amount of working space. The kitchen has a double gas burner, and the provided large wok (which fits in the curved left burner) is great for cooking Chinese veggies. The apartment is also tastefully decorated; I especially like the rainbow rug which gives the whole place a really inviting feel. The bed is very comfortable, with just the right firmness, and has a sturdy frame with a comfy backrest that's great for lounging. Hua is a friendly host and was attentive to issues that we raised.
There are a few issues with this apartment however. One is sound insulation: there is poor sound insulation between this apartment and the neighboring apartment (which is also owned by Hua and also operated as an AirBnB unit). At one place in the apartment, the only thing separating this apartment from the neighboring one is a thin piece of opaque glass, which is a really poor design; this glass should be removed and replaced with something thicker. On the other side of this glass is the neighboring apartment's toilet, so when your neighbor vomits at 1:55 AM (which happened to us), you will hear everything. This problem isn't unique to this apartment; I've stayed in 3 apartments so far in Taipei and 2 of them had noticeable sound insulation issues.
The other major problem is the water heater. The water heater in this apartment shuts off when the hot water flow rate is too low, and this effectively means that the water coming out of the tap will always be either cold or very hot. If you try to adjust it to a warm temperature midway on the dial, the flow rate will be too low and the hot water will stop, and you'll be left with cold water. I did eventually find a trick for dealing with this: since the bathroom has two shower taps, you can set one of them to the hottest setting and just let the water flow down the drain (which wastes water unfortunately), and then use the other to shower. The hot water flowing out of one tap ensures that the flow rate is high enough to keep the hot water coming, allowing you to adjust the hot water flow on the other tap as much as you want. Another way of dealing with this problem is adjusting the temperature on the water heater unit on the roof (ask Hua to show you where it is), but this just changes how hot the hot water is, it doesn't change the fact that you can't set the water to an intermediate temperature. I haven't seen this issue at any other property I've stayed at (in Taiwan or elsewhere).
There are a few other minor issues. The wardrobe has a funny smell and some of the drawers are misaligned and don't open easily. The shower is in the same room as the toilet without any divider and so you get the ground around the toilet wet when you shower (I know this style is common in Taiwan but most apartments I've stayed at do have a partition). Several appliances (refrigerator, air conditioner, sink) malfunctioned while we stayed but Hua was quick to replace/repair them.
The location of the apartment isn't very central (this is ultimately what led us to move out; we wanted to be within walking distance of attractions in central Taipei). It is however very close to a Brown line station, and 15-30 minutes on the train will get you to most places in Taipei. It's also very close to our favorite restaurant in Taipei, 休閒食堂, which hosts an all-you-can-eat vegetarian home-style buffet for NT$100 a person. Don't miss this amazing restaurant! It's right next to the station and will help counterbalance all the sugary fried food that one inevitably binges on in Taipei. The path along the river nearby is the start of a great bike ride that will take you all the way to the mouth of the Tamsui river if your legs (and butt—those YouBike seats aren't the most comfortable) can take it. I did this ride once and I think I paid around USD$7 for a 5 hour YouBike rental; I stopped for lunch midway at Twatutia. You can then ride the train all the way back. Also in the neighborhood are the Taipei Zoo and the Maokong Gondola, which are good for a day or two of entertainment.