I'm evaluating it...it is reliable? fast? secure? Does anyone recommend it, or suggests to stay away from it?
It is reliable, fast and secure.
You will need to evaluate whether or not it is a good match for your requirements.
If your app is a simple web application with lots of reads and little writes, Azure would be a great solution. On the other hand, If your app is going to be hitting SQL Azure pretty hard (writes and reads) I wouldn't trust it. We have an app that's fairly high scale and does lots of data processing. We are having terrible experiences with the database just crashing and returning timeouts for upwards of 10 minutes. Sure it comes back fine but as soon as we start pounding it, it will crash again. We don't have the same issues on a physical database.
If you have the option of using their tables storage engine as your backend, you shouldn't have any trouble. It's quite fast and reliable.
With regards to security, it really depends on what you're looking for. If you need to lock down requests based on IP addresses (such as for a secure intranet), you will want to do that in your code instead of through the web config or IIS. We have encountered several times where Azure will simply lose those settings in IIS and your app is suddenly open to the world.
In short, I don't trust them for anything mission critical. Rackspace and Amazon on the other hand, I've never had any trouble with them.