Breath direction the same on adjacent holes--so legato pentatonic patterns.
Not C so much, although C E G
F has F A
G is great! A B D, also E G
Bb is good too, Bb C (2 ways, and if you do it with the button, the D is there too--and without the button, G Bb), D F, F G if you use the button--but mostly I mean without the button, so Eb is also a good key, as is Ab--Db not so much, Gb some, B actually pretty good (G# B C# with button in, D# F#).
D is good on paper, I'm trying to get better at it.
Gary