For customers running older versions of SQL Server, I'm happy to report that the Azure SQL managed instance supports backward compatibility to SQL 2008 databases. It supports direct migration from SQL 2005 database servers, however migrated SQL 2005 databases will have their compatibility level updated to SQL 2008.
A great benefit of choosing the managed instance deployment option is that it will always be up-to-date because patches and upgrades are automatically applied. Also, you don't have to purchase, manage or secure physical hardware.
Managed instance has High-availability built in and pre-configured using a technology similar to Always On Availability Groups, providing 99.99% uptime SLA. It also has automated backups and point in time restore.
With the managed instance you will spend less time on administrative tasks because the service either performs these tasks automatically for you or greatly simplifies them.
It supports Azure AD authentication as cloud alternative to Windows authentication, automatically manages XTP filegroup and files for databases containing In-Memory OLTP objects and supports SQL Server Integration Services (SSIS) and can host the SSIS catalog (SSISDB) that stores the packages. SSIS packages must be executed on a managed Azure-SSIS Integration Runtime (IR) in Azure Data Factory (ADF). Unlike Azure SQL Database, it allows cross-database queries.
There are two service tiers for Managed Instance: General Purpose and Business Critical.
General purpose: Designed for applications with typical performance and IO latency requirements.
Business critical: Designed for applications with low IO latency requirements and minimal impact of underlying maintenance operations on the workload.
Server sizes range from 8 to 80 vCores depending upon service tier. Memory is 7 GB per vCore.
Maximum storage is 8 TB for general purpose and up to 4 TB for Business Critical
NEW Stuff in Azure SQL Managed Instance!
As of 11 April 2019, managed instance now has a public endpoint. (YAY!)Here's a link to the official Microsoft article on it - with full instructions for implementing it via Powershell