The Loft is a really lovely, clean, comfortable, space to be in and the hosts have thought of everything to make it a home from home. I slept really well and wasn't bothered at all by the train line, which is just opposite (it's above ground tube trains so much quieter than mainline).
I have fibromyalgia so am like the princess and the pea when it comes to beds. I was really comfortable on the good quality foam mattress. It was also great to have a bath, for the same reason. And, again, because of fibro, I'm really sensitive to smells and I was so delighted to find that the bedding hadn't been washed with strong smelling products (I noticed some ecover powder in the flat, which is what I use at home and imagine many people with sensory issues or sensitive skin do too).
Lyla was so easy to deal with and check in, parking, and check out was about as straight forward as it could be.
The tube station is very close - about a minute walk, and because it's zone 3, the tube was not too busy, even in morning rush hour.
Obviously being in the attic, there are quite a lot of stairs up to the flat. That said, I arrived after playing in a concert and was able, with a little effort, to get my double bass up there. If you have mobility difficulties or need to come and go with a heavy item, you might want to consider this.
I'll definitely be back next time I'm working in South Kensington for a few days.
Thanks, Lyla!