A major benefit of SQL azure is the pricing model, you do not have an initial cost like when you buy your own SQL Server. Imagine you need a SQL server database with 99.9% availability and the cost for that server. You need at least two servers in a cluster, redundant power supply, redundant network/internet access, two storage arrays in the SAN with synchronous replication and they have to be located at different locations. That sounds cheap doesn’t it? No? You are right! Also imagine that you need to handle heavy load once or twice a month, or why not once a year. You need to buy a server with enough resources to handle the peak load and if the peak is only once a year. What a waste of resources!
Well, you can always consolidate your database with other databases, but do you get enough resources when you really need them? It is not unusual that your database servers will cost $200 000 with SQL server licenses and SAN excluded. Well the SAN can be shared for all servers in your network, or can you? Yes you can, but do you get the performance you need? Your SAN technichians will ask you how many GB you need and not the number of IOPS you need, and that is two completely different things. On top of that you need a backup solution to handle your backups, or do you trust the SAN? Well, don’t do it! I have seen two major outsourcing companies in Sweden relying on the SAN and it was an expensive experience for them, loosing a lot of money and reputation. To small companies or startups this can be heavy cost and big risk and to avoid this investment you can move in to SQL Azure, with no initial cost at all!
You only pay a monthly fee for what you really use. You can start with a small database and pay a small fee and grow as you need.
That is what I like with SQL Azure.