@Daniel Tourde: 'apt install cinnamon' don't install the meta packages but only the main component and its deps. For install the meta packages that include login manager as recommends (that are installed by default) you need install cinnamon-core or for a additional software for a full desktop use cinnamon-desktop-environment (same used by tasksel, or simply install cinnamon using tasksel that include also task-desktop). When cinnamon was added also in DE selection in debian install I tested it and was ok, on 4.6 (and probably also 4.4, I not remember good) I not tested clean install of debian with cinnamon but only upgrade on existant Sid installation, if for unexpected case something important is missed please tell me it.