In CRM 2015 there are a number of nice new features I wanted to point out to you..
First of all there is the possibility to execute multiple requests in one go in such a way that if one of them returns an error none of them will be executed. This is somewhat similar to a database transaction..
Second one is that we now have an entity that stores tracing information. If you want to write errors and debug info from plugins and such you can now see them via the CRM interface in stead of viewing them on the server in some text file, which would not even be possible in a cloud version.
Sadly this feature is not available in the CRM 2015 on-premise version but will also be included in the next on-premise update.
What comes in very handy as well is CRM now supports an Upsert command directly. Before this you would have to do a retrieve and if the record did not exist do an insert else an update. Now the SDK handles this automatically for you.
Last but not least there is a solution for the birthday problem I described here. Now you can specify if a date is time zone independent and should display a date only.
Be sure to check out the rest of the new features but these where my favorites.