Is the change worth it? It depends, for example, on which mobile phone you have. I had a Huawei mobile phone and a Samsung Watch and I kept getting disconnections. But that's another topic.
I read up on the watch myself and the battery is supposed to be really great. So at least a week!
I couldn't find out exactly how good the speaker is from my research. But that's also a matter of taste.
And the watch supports Spotify, of course in connection with the smartphone.