Web transaction types (seen in tooltips) should now be more meaningful. When you mouse over a transaction, instead of showing Action it will show ASP, MVC, WebAPI, WebService, WCF, etc.
This improvement to transaction naming may impact the transaction names of existing metrics including Key Transactions, Alert on Anything metrics and Insights queries based on transaction names. These would need to be recreated with the new transaction name after the upgrade.
The agent will now fallback to using the proxy configured for the executing user when talking to New Relic.