Mathew's place was picture-accurate. Pretty standard room for a Tokyo family of three or four.
I do suggest to treat wheeled luggages as half a person because the apartment isn't exactly spacious enough to hold more than one luggage per user, and four luggages may be the maximum.
So ideally, the apartment would best suit three people with one luggage each in terms of space. If you're traveling light, no problem. Also, the space between the sofa bed and fridge is pretty tight; just enough to open and close the fridge door. If you're the type who likes to buy a lot and keep them inside the fridge, think twice.
The often complained about bed in the kitchen wasn't as bad as some of the reviewers say. I mean, it's a sofa bed. You don't expect a sofa bed to feel as comfy as a regular bed. It does a good enough job when it comes to sleeping comfortably after a long day of walking and climbing stairs.
The one thing I feel like I'm obliged to tell future users is the size of the extra toilet. It's probably best used either by kids or short people because the leg space ain't that good. So, if you're a family of 5'8" and up, I'm not sure you'd "fully utilize" it.
Apart from the toilet size and overall apartment space, everything was just as advertised. Near Mita Station with a direct transfer to the airport and near Shiba Koen for easy access to major tourist spots. You can literally walk to Tokyo Tower in 15 minutes if you wanted. I did a lot of night strolling with Tokyo Tower in sight, and it was amazing.
The apartment had a separate pocket wifi and internet which was a huge plus. It's also surrounded by restaurants and convenience stores. It's near the main highway for easy taxi access, but far enough for a good night's sleep.
So yeah, pretty okay apartment overall.