I stayed at Base2Stay for 2 days in April. I was traveling alone to visit universities in London, and wanted to stay somewhere clean, safe, and with convenient access to the tube. Base2Stay met all these conditions and exceeded my expectations.
I booked a double room with bunkbeds online, as this was all that was available, but at the front desk I was able to switch to a single room without a problem. The room was very compact but well laid out, with a single bed, desk, flat screen TV mounted on the wall, built-in kitchenette and closet, and a fairly large bathroom with a great shower. Everything was clean and new. The decoration was tasetful and modern--it didn't have much personality but for 90 pounds a night I wasn't expecting it. It also had internet through the TV for free, which, while difficult to use, still allowed me to check and write email and browse the Internet. For convenience I ordered the breakfast box for an additional 3 pounds, and got a ton of food--cereal and milk, orange juice, nutrigrain bar, some sort of muffin/cookie.
The hotel is about a 5 minute walk to Gloucester Road tube station, but also convenient to the Kensington area--the V&A and Natural History museums are about a 15 minute walk. Nearby tubes are on the District and Circle lines, with easy access to Paddington station for the Heathrow Express.
Overall I thought this was particularly good hotel for the price. I've stayed in hotels in this price range in London before and found them to be a bit older and more dingy, so this as a great find.