The latest update at Zoho Planner addresses some of the major usability issues that you users have pointed out. Though AJAX has been a boon for the whole web with its non-loading pages, easy drag-and-drop etc, it can cause problems too (as compiled in this famous list of Ajax Mistakes).
One of the major flaws was breaking the browser’s back button functionality. This is now addressed in Zoho Planner. You can now move from one page to another and use the browser’s Back/Forward buttons to navigate. Going further we will be addressing the intra-page navigation too and expect them to be carried over to other Zoho apps as well!
The top ‘Insert’ menu has given way for a sleek menu bar with direct links. The link to iCal has gone inside the ‘Settings’ menu and the Add List Item/Reorder have gone to the bottom of a list (they were on top previously).
Do give the new Zoho Planner a try and do let us know where we need to improve.