What a clever way to disguise the "TW release date when?" question.
On topic though, clearly the part that takes the most development of games with an engine made from scratch is well, making the engine and all the game mechanics work with as little bugs as possible. Things on a more superficial level, like actual game stuff (weapons, quests, particular NPCs, etc.) are always left for the end of the whole process because it'd be pretty stupid to try and make a quest with a lot of buggy and unfinished features, or to make the models for weapons before combat is made, etc.
The thick part of the game looks mostly complete, at least for multiplayer. Single player definitely has a lot more features since it's not mostly combat, and we haven't had many updates in this area so there's no way to be sure about how complete it is.