I left blackberry when my company switched to Microsoft Exchange server. Emails would only sync every 15 minutes or so unless i purchased blackberry BES. The IT department tried everything including tweaking settings on both the server and the device... Gmail emails came instantly, but exchange emails took 15 minutes (which was usually 16 minutes too late
I did love the keyboard and thought i had everything and would have a BB forever...boy was i wrong. My Samsung Galaxy S5 is light-years better. The only thing i still miss is the keyboard but SwiftKey helps.