Since starting to use MixMax, I permanently ended the quest to find a better email interface for Google Apps (Gmail). With MixMax, I can instantly transport information out of email via sharing link and into project management tools, notes, and any other partner collaboration.
The calendar scheduling feature is the first and only one I've ever found that actually makes scheduling faster and easier for the calendar invite recipient as well as me. I've taken meeting scheduling from 5+ emails back and forth + a cal invite down to 1 email, and that's it. It's brilliant, and saves me hours each week.
Their email template functionality blows Gmail/Inbox's built-in options out of the water, making it actually logical and easy to save, edit, and use email templates.
I also use it to schedule emails. It offers smart scheduling, which is great for sales, but I mostly use scheduling to only bother my clients/leads during business hours with new emails and space out emails as needed (account managers, you know how important that is).
The YouTube video embed tool has proven to increase my tutorial viewing rates when I send client's instructions because they don't have to leave their email to watch the video.
MixMax also has a robust set of sales automation, but I don't use that part much, not big enough to need much sales automation.
I've probably cut email communication time down by 1/3 since incorporating MixMax. Don't know how I lived without it now.
Now the only thing I long for on MixMax is a mobile app so that I can schedule meetings and share emails on the go... I know they're working on it.