They just had their first major overhaul in the last decade+ and are looking pretty shiny:
Personally I haven't had a chance to check it out because I just use my browser for personal email & my work mail is hosted through Microsoft so there's no pretending not using Outlook at work does anything for me.
That said, I am eagerly waiting for them to give the same treatment to the soon-to-be merged Thunderbird & K9 mail so I can use that for my personal mail on my phone