There are some important additions, such as clustering and failover support, and a few niceties like user-defined functions and indexed views. Upgrading the data format from 7 to 8 was seamless, but replication was painful. Gone are the Enterprise Manager HTML-based pages at the machine level, replaced by a small maze of things to do to make replication happen. We finally had to reinstall the server to make replication happy. The help file on this topic is a joke. It reads something like "Step 1, configure replication. Step 2, start it up." with absolutely no detail.My bottom line: take your time in upgrading.