Oliver and Marcus's place was fantastic for my week long stay in London! Very central to get around via bus, tube, or walking with lots of convenient pubs, restaurants, and stores around (I recommend The Bite - a small Italian place with delicious takeaway pasta dishes).
The room was perfect size for me as a solo traveler; plenty of space for my bags and items. The bathroom amenities were super nice and clean and the whole apartment was very well decorated and homey :)
I got a little lost trying to get to the unit the first day, so make sure you have a good route planned before making your way. Once you figure it out though, it's not difficult to find your way back.
While I didn't get to socialize with Oliver and Marcus much since I was there during the week, they were very pleasant company when we did cross paths. Marcus was nice enough to order food in for me my first night since I had traveled up late from Brighton and not many places still had their kitchens open on the bank holiday.
My only "issues" (which aren't actually problems at all) was that the bed was a bit firmer than I'm used to, so that took a bit to adjust to for me personally. There was also construction going on right in front of the apartment, but if you close the window or have earplugs that shouldn't be a problem. The wifi was also a bit dodgy at times, but when I mentioned it Marcus said they could easily just reboot the router or fiddle with the booster.
Overall, definitely recommend Oliver and Marcus's flat for someone needing a cozy base around London! :)