The first thing I wanted to do was to add a feature so I could add a task to my to-do list software which is not supported by Alexa. It turns out that you cannot construct a sentence along the lines of "Tell Asana to add a task: <task>". You can't actually have a 'slot' which contains a freeform piece of text, even if it is the last piece of text in the sentence.
The Alexa API differs between regions, so the North America version of the API supports this but the EU version doesn't. It was removed from the NA version for a while but placed back after a bit of an uproar.
I think you could develop some more useful stuff using Alexa if only this feature was consistently available. I cannot think of a good reason why it isn't.
I now just mainly have it as a Spotify speaker, and occasionally I use it as an expensive egg timer. I normally have it on mute because I find it activates and starts recording private conversations. I don't see it getting better.