I've tried 2.0 before, but it lacks having the drop down view menu to the left of the the message search menu which allows you to view messages that you have "labeled", "people I know", "has attachments", "recent", etc. Is this feature actually on 2.0 but hidden or can be resurfaced with an extension?
Also, having the search field on top along with the toolbar icons limits the number of icons I can put up there (I use the lightning calendar, so that adds 5 more).
Also, the lightning 0.7 update takes the calendar away from underneath the "Local Folders" and forces you to reduce the width of the email screen to see the calendar and the tasks, is there a way to set 0.7 to have the original view or is it best to just stay with the 0.3. The only difference I liked was that it put the color codes next to the different calendar labels, but that's not a huge deal.
is still there
If you go to View-->Toolbars-->Customize
then one of the 'buttons' you can drag onto the bar is the one that you are looking for.
As for the calendar bar on the right, I don't know of any way to revert to the previous format, but you can close it completely, and just flip to calendar view when you need to, that way the mail gets full width again.