Frustrating because it was just a couple things short of being absolutely perfect. The location is fantastic (though a bit noisy if you don't live in the city -- we do so it wasn't a bother for us). Bars, restaurants, shopping, a great Sunday market taking up the street right outside the door with all kinds of fun stuff, Tube station across the street, an Eataly 30 seconds from the door for great night time gelato runs. Brought my family of 6 (4 kids aged 16, 13, 13 and 10) -- the bed situation was great. Having 2 sofa beds in the living room worked out well. My kids loved this location. Asian food (we're Asian) all over the place, the Polo Bar around the corner with 24 hour bangers and mash and mac and cheese was great in a pinch. The Tesco around the corner made grocery runs easy keeping us stocked with water, drinks, ice, etc. The place was spacious and clean. The host -- a commercial outfit that appears to be a real estate investment company or something that has several places to rent including most/all of the flats in this building -- was very communicative, and their check in instructions and such were great.
So what was the problem? Nothing that was a deal breaker, but they were annoyances that make the title of "Luxury appartment" a little bit of a stretch. This place could be *perfect* if it wasn't for these little hassles.
1) It's been hot in London and there's no air conditioning. That was OK because they advertised no air conditioning but fans in the rooms. Fans don't do well if all the air is hot -- that's a convection oven. You've gotta open the windows. The place has windows on both sides of the room for a great cross breeze cooling opportunity in the evening. However, many of the windows are *so* hard to open. They are great, modern windows installed poorly such that they require serious muscle to open them, and some of them open only 5-6 inches. Also, there are no screens on the windows -- so mosquitos come over night and bite you. My kids got a bunch of bites which drove the crazy, but it was that or no sleep because it was too hot in the room.
Side note: Brits love their pubs and the street this place is on is wall to wall after work pub goers that stay out until at least 11pm on week nights and later on weekends. Closed, the windows did a pretty good job of blocking out noise. It was fairly loud when open -- again, not as much of a showstopper for us as we live in the city, but others might want to consider.

2) The washer/dryer worked, but didn't. With a family of 6 trying to do a 16 day trip with only carry on luggage, it was critical to have a washer/dryer. I booked this place because it had a dryer. However, when in Dryer mode, it would Error out with an alarm and error code that would run for 1-10 minutes then continue on. It would do this repeatedly in a cycle but eventually complete. This first happened after midnight -- we washed a load and put in the dryer so we could use things the next morning. The buzzer rang and wouldn't stop. My kids were exhausted and asleep so I couldn't let the buzzer ring. I cancelled the dryer with the intent to hang dry what I could, but canceling the dryer didn't release the lock. The manual release level was covered by the built in cabinet so there was no way to get the clothes out that we needed for the next day. I fumbled around in the dark trying to get it open without waking the kids that night, then again the next day. Eventually the next day, we ran a quick wash cycle which worked fine and it unlocked so we could hang our clothes. I then washed a couple room towels and the dryer to try to troubleshoot and that's when I found out that the error buzzer would eventually stop and you could restart the cycle by pressing the pause/restart button. The staff was communicative about it and even came to fix it, but because of the nature of the problem, they thought they fixed it, but it wasn't fixed. It still errored consistently.
3) Other little things that were broken but were just aesthetically broken, not functionally broken like the bathroom toilet flush panel that kept falling off, or the water damage to the plank flooring, or the fan that turned, but didn't move any air (which they replaced the next day when told them about it).
Would I say here again? Sure, now that I know the place's quirks, but not for more than the rate I got. However, if Iconica put just a little bit more money into this place, dealt with these nuisances, and met the "Luxury" designation in the title, it'd be worth 30-50% more per night, and I'd probably pay it.