How to Check What Shared Mailboxes a User has Access to via Exchange 2010 Power Shell

I need to run a power shell script that allows me to see what shared mailboxes a particular user has access to.  I have tried running the cmdlet below but its not working.  Im using Exchange 2010.

Get-Mailbox | Get-MailboxPermission | ?{($_.AccessRights -eq "FullAccess") -and ($_.User -like 'DOMAIN\user') -and ($_.IsInherited -eq $false)} | ft Id*

I change the domain\user to replicate my domain and users alias.

Is there any other power shell i can use to pull of what i need?