My family and I really enjoyed our stay at Joe's apartment. We have a 1 year old and found the high chair and pack-n-play to be extremely helpful. We also enjoyed cooking in the beautiful kitchen.
A couple of notes from our stay. The bedrooms were very bright during our June stay. This wasn't an issue for our group, but you'll likely want to pack a sleep mask if you need total darkness to sleep.
This is an apartment so you can hear your neighbors. This isn't any different than any other apartment I've ever stayed in, but it's worth mentioning as we inadvertently disturbed the downstairs neighbor when we moved one of the kitchen chairs too early in the morning.
There are two grocery stores within walking distance as well as many great restaurants and bars. We walked back and forth from Pike Place Market a couple times. It's a bit of a trek pushing a stroller but very doable weather permitting.
Overall I'd highly recommend Joe's place for anyone visiting Seattle!