I have recently started moving customers across to Office365 in earnest. I have been very impressed by the level of functionallity backing the Office365 offering. Via PowerShell, I have yet to find a significant limitation in the online Exchange.
I recently had to transfer a domain where the website code referenced domain.tld instead of www.domain.tld. The Office365 domain management page doesn't allow an 'empty' A record to be created. However to achieve this, simply use the @ symbol for the host name.
Credit to this thread on the Office365 communities http://community.office365.com/en-us/f/146/t/2102.aspx
