I have a feeling MB's autocompletion feature is not what it should/could be.
First:
I support Tompeto's earlier suggestion to autocomplete ONLY the first value (artist, composer, genre) that you are typing, not the complete range of values that other field(s) has/have. As he said: "When filling some fields of an album, like composers or musicians credit list, for instance, it would be very useful to have the auto complete suggestions feature to point suggestions to individual tag values, instead of only show the whole tag with all its values."
Second: with multiple values/names in one field, the autocompletion works only for the first name. If I want to enter Frank Sinatra; Dean Martin I expect Frank Sin... to show 'Frank Sinatra' only, after I have entered him and continue typing Dean Ma... should lead to Dean Martin. That is not the case.
Third: the autocompletion is not really autocompletion. It is 'autosuggestion' (and not as in the mental illness with the same name).
It only suggests a name or value, you still have to select it from a dropdownlist. That makes sense as long as the typed characters still leave multiple options open: Georg... could still become Georges Brassens, George Moustaki, Georg Friedrich Händel and many many more.
But as the typing continues and the options shrink, the moment comes that only ONE option is still open: Georg Friedr can hardly be anyone else than Georg Friedrich Händel.
At that moment I would hope/expect MB can really autocomplete the input.
It doesn't.
If in the genre box I type CH it should be enough to automatically CHRISTMAS to be entered, because there are no other genres in my list starting with CH. Instead I have to move the cursor down to the one-option-dropdownlist, select CHRISTMAS and click to confirm.
It even happened a few times that I had typed CH and then ENTER to confirm my choice. The result was a NEW genre, called CH.
Could it be made more smooth in a future version, please?
In any dropdownlist?
And an earlier related question got no reply yet, so please allow me to repeat it here:
Why have some fields (such as conductor) no autocompletion feature? Why treat them differently from other 'involved people'?
I would strongly suggest to make all text fields (except title) autocomplete fields.