Any new product have improvement with its older version and some of features are removed to provide better design, like wise in Exchange server 2010 the below features are removed or no longer available.
1. LCR (Local Continuous replication) and SCC (Single Copy Clusters) are no more available in Exchange 2010, you can use Database Availability Groups (DAG), using this feature you can easily provide high availability, disaster recovery, and backup solution for messaging environment
2. Even CCR (Cluster continuous Replication) and SCR (Standby Continuous Replication) has been removed or combined and presented a new feature call Database Availability Groups (DAG)
3. There is no Storage group in Exchange 2010, all Mailbox databases is managed in origination level not in server level
4. Mail box can only be created from the Exchange console, not like the earlier versions you can’t use Active Directory User and Computer for creation user mail box in Exchange 2010
5. Exchange tasks are only be done through EMC (Exchange management console)
6. You can’t install Exchange 2010 on Windows 2003 and the earlier versions
7. Routing group connector (already removed on Exchange 2007) for some scenarios it’s required for co-existing with older mailing system or older exchange versions