I'm frustrated because I have made a huge switch. I moved my CRM to Zoho and my email to Zoho mail and gave up Outlook. I now use the Zoho CRM Calendar and have been pleased until I realized there is a difference between Zoho Calendar and CRM Calendar.
Even though I'm using Zoho Mail from within the CRM it wants to put meeting invites iinto the Zoho Calendar instead of the CRM. While there is a option to add CRM activities to the Zoho Calendar the opposite does not exist. I find this really cumbersome. I came to Zoho thinking it was a CRM but it seems they like to cater to the free services they offer more than the paid ones. As a CRM user you should have the ability to pick which calendar you'd like to be your default.
In the same vein, when you create a contact from an email in Zoho Mail (being used within the CRM interface) it creates a Zoho Contact. Not a lead or a contact in the CRM but a contact in another application I don't currently use. This should also be a feature where you can pick where that new contact/lead can be added from within the email module.
Just my two cents...