Great place and would consider staying again. It was CLEAN, looked recently renovated, and staff were very friendly. We got a room for a family of 4 (double bed + 2 twin beds), which was in the basement. Continental breakfast was good, no surprises there.
The hotel is on a quiet street full of hotels (which look like they're re-purposed apartment buildings), and it's around the corner from a subway station. The subway station is on a busy street with convenience stores and a variety of restaurants (incl. Indian, halal, pubs, and a McD's).
The only reason im giving it 4 stars is because the room has very few complementary amenities. It had hand soap and body wash, but you'll need to bring your own shampoo, etc. But, maybe that's why the Trebovir is a little more reasonably priced than other hotels (for London, anyway).
The next time we visit London, we will definitely check the availability of Trebovir when considering where to stay.