It seems that (at least in the Mac version) that there are several limits to the ability to organize the People, Projects and Tags. People seem to be given top billing, which is great for teams but not for individual users since it burns a lot of space. Can the order of People, Task and Tags be set to be adjustable (or even hidden)? If you're using Producteev for personal project task management it makes more sense to have your Projects or tags take precedence and focus. Even if you are on a team, you should be able to change your focus to Projects and Tags.
And along with others that have mentioned it: the ability to make the left-hand navigation bar wider. Limiting it is fine. Making it smaller than it was before is a problem if people have their workflows based on that width being a certain size.
Adding on to this, for individual users, the "Assignee" and "Followers" fields are redundant...I suppose there's no way to hide that? And as for navigating the left-hand bar, in the previous version, you could order workspaces by dragging and dropping them. Is there a way to do this with projects, without having put numbers in the name to put them in the order you want?