I like the different interface, its not very intuitive.
I added 3 account. comparing the unified inbox to any other inbox, i did not know which emails were in, which were read and which were archived. Moreover the bottom part of the email list was continuously changing (appearing then disappearing, then new emails appearing) and the connectivity disk at the top menu bar was constantly and erratically swirling. Not sure if its indexing or its a bug.
In any case i would love to use it when its running smooth and would love to have the same on OSx
Dan911A about Spike - Email & Team Chat, v1.3.9