Overall London Backpackers was amazing on my trip! Just a few points that were annoying, but nothing WOW:
1 - The boxes under the bed are always stuck under the bed, I bothered people who were in bed several times because I just couldn't get them out of there!
2 - Bathrooms were always full and they are extremely difficult to use. I'm an architect and I've never seen a door open to the inside and not have space to circulate. It also had few spaces to support clothes. Other than that it's very clean!
3 - Beds are comfortable but slightly noisy.