There’s one important area in which AutoCAD 2013’s Help shines when compared with its immediate predecessors. If you’re a Visual LISP user, you’ll be pleased to know that if you select a function name in the editor (e.g. (vla-get-ActiveDocument)) and hit Ctrl+F1, this now takes you to the appropriate page in the ActiveX and VBA Reference, as it should. In AutoCAD 2011 you just got a cryptic message or a 404 error, depending on the context. In AutoCAD 2012, you were just taken to the front page of Help and expected to find it yourself. Props to Autodesk for fixing this problem.
As a bonus, the reference you’re taken to is still a CHM so it works nicely. The Search tab doesn’t work in Windows 7, but that applies to all CHM Help and it’s Microsoft’s fault, not Autodesk’s. The structured contents and index are fully functional, which makes the whole thing usable even without the search facility.