Well I tried out the trial of Office 365, and from a subjective point of view, as I work in the Hosted Exchange industry, it seems to have it's ups and downs:
Pros:
Was very quick and easy to setup a trial.
The panel interface is pretty nice.
I didn't need to use it, but having a SharePoint site would be useful for most businesses if they don't already run one.
Very cheap!
Cons:
S/MIME is not supported in Office 365 OWA.
I wanted to use the Remote PowerShell commands, but the guidance on how to use this was hidden away and took a bit of time to find.
I sent an email to my @outlook.com address, did not get delivered, did not get NDR'ed. Still wondering where that one went.
Everything was assuming I was in the US, all the time zones/languages for everything etc.
Initially my Lync integration into OWA would not work, started working after a while though.
If anyone can answer how they stop spammers using the service I would love to hear it, it looks like you can send out emails as soon as your trial is ready without any billing info, surely this is being abused by spammers!
Also you can tell the driver for removing the EMC from Exchange 2013 is to improve the user experience for Office 365 users, who can only really use the web based ECP tools:
http://exchangepedia.com/2012/07/exchange-2013-dude-wheres-my-exchange-management-console-emc.html
Couple more cons off the top of my head:
Patriot Act
Can't guarantee your data is stored in the UK
How is their support by the way? decent? not had to use them?
Edit - my emails finally got delivered to my outlook.com address 5 hours later! Looks like it got stuck on one of the Hub Transports for Office 365:
Received: from AM2PRD0311HT001.eurprd03.prod.outlook.com (157.56.249.149) by
AM1EHSMHS008.bigfish.com (10.3.207.108) with Microsoft SMTP Server (TLS) id
14.1.225.23; Wed, 26 Sep 2012 23:19:44 +0000
Received: from AM2PRD0311MB434.eurprd03.prod.outlook.com ([169.254.11.64]) by
AM2PRD0311HT001.eurprd03.prod.outlook.com ([10.255.162.36]) with mapi id
14.16.0190.008; Wed, 26 Sep 2012 18:19:36 +0000