For Smart Phones...both iPhone and Android...Microsofts relatively new (and free) Outlook client. Looks and behaves a lot like Outlook 2013.
https://play.google.com/store/apps/details?id=com.microsoft.office.outlook&hl=en
https://itunes.apple.com/us/app/microsoft-outlook/id951937596?mt=8
Only feature I don't like, enabled by default, is the "Focus" feature...but it's quick and easy to simply turn off. It's like their new "Clutter" mailbox version on the smart phone client.
Plus now that O365 has a built in Mobile Device Manager....managing the clients fleet of smart phones is easy.
Explaining the advantages of O365 to clients....fairly easy sell.
POP is an old protocol...came out back in the dial up days, when people generally had just 1 computer. Designed for 1x client. EMailed pulled down and stored on the local computer. Yes yes you could configure several computers and check the box to "download but don't delete from the mailbox"...but we all know how sloppy that gets.
IMAP..a more recent mail protocol...works better for multiple devices...but as we have found, inconsistent. Mostly due to the variety of hosts and clients. Still ends up being a headache to manage...and it's not very universal across all devices.
Hosted Exchange, with proper Outlook clients...designed to work together, smooth. All devices can be the same, very universal. Equal access from all devices. Easy access from anywhere.
A fairly decent spam/virus filtering system is built in, Microsofts ForeFront. No additional cost.
Depending on what package you get, the "retention policies" and eDiscovery option.
Depending on the package, the availability of the "FULL" Microsoft Office suite...which can be installed on up to 5x of your computers concurrently. You have a perpetual rollling subscription to that full Office suite. New version comes out...you get it!
Backup...well, we're still wrapping our heads around this. But the retention policies...ability to go back and pull e-mail that was deleted/lost...covers the needs for most. It's generally considered that you don't have to worry about full backups or disaster recovery...a fire won't take out the server, the server won't crash...since Microsoft has it all spread across cloud data centers. For for "most" SMBs...it's fine. This is worth of another full thread so I don't want to dig into that here...since O365 exploded in the past year or two...backup options for your data up there are still coming out and being discussed.
I don't have heavy users of OneDrive yet....just light users. I use it myself...and love it. I am looking forward to the new OneDrive coming out this fall that addresses many of the current limitations.
Going back to public folders....having a "company calendar"...or having "company contacts", or having mail enabled public folders...once you show the clients the advantages of those, how the office can gain from using them, along with distribution lists, etc...clients get enthusiastic about those.
Sharepoint....I'm hoping that improves....I've been voicing to the new development guy how much "mapped cloud drive" support is really needed, and the ability to tie that in with an on-prem server. It works fine via browser access...but people still love that mapped drive feature. (and I'd love to see it sync with the servers Company Folders). I encourage others here to voice that desire to the OneDrive/Sharepoint team...get up on a soap box and shout!