As Himanshu has stated Lumia 525 would be perfect for you. Because 512 mb devices are having less apps.
Now to your question, Windows Phones are good only when you are not dependent on Google Services. Apps likes Google plus, Hangout, official gmail or any other G apps are missing. Only google search is available(although I don't use it as we have Bing).
So if you are happy with not having them, then you would be loving the experience WP is gonna offer.
Another thing is that app developers usually ignore this platform, So let's say BBM is still not available. But it's improving with good momemtum.
So if you are an app addict and love to test new apps, then you've got to increase your patience. The wait could be of 1 week, 1 month or even 1 year.
But apart from all these problems, You will soon find the platform very well developed and love its uniqueness. If you want to get into Microsoft ecosytem then it's a good time to start.
Extra Note- IMO Google is really going down in wrong path. They have changed their privacy policy and seems like they are becoming real real adsellers. So, forget about any kind of privacy you would have.