This is what the Tube network looks like if you can't use stairs. (Or, rather, what it looked like about a year ago...several recent improvements are missing, with more on the way.) Looks like you're sorted if you live in the Docklands, but screwed just about anywhere else. The Waterloo and City Line becomes (or remains, depending on your level of cynicism) totally unusable.
The map appears to originate from Transport For All (@transportforall), a charity which campaigns for better accessibility across transport. Meanwhile, Diamond Geezer makes regular sport of the subject, with spoof Minutes from an accessibility meeting and a spurious guide to wheelchair symbols on the Tube map.
To get the other side of the story, visit TfL's Step Free Access pages, which do offer plenty of guides even if the situation they reflect is far from ideal.
See our Guide to Alternative Tube maps for dozens of other cartographic bastardisations.