I spent several years learning to play the recorder, with the help of a co-worker who had quite a bit of experience. I can (or could) play soprano, alto, tenor, and bass recorders (with varying degrees of mastery); but there were some things I never managed. A recorder’s range is a little over two octaves, and I always had trouble with the highest notes. They often involve half-hole fingerings, and you have to control your breath very precisely, and the odds of my getting any of them right on any particular recorder was never all that high. And trust me, when you screw it up everyone notices.
I’d been told that the penny whistle was generally easier in that regard; and that the Clarke Sweetone was more forgiving than most. I can’t say much about the latter point, as I’ve no experience with other whistles; but I can honestly say that the whistle fingering for the upper register is so much easier that it takes my breath away. After a week I am playing tunes using notes that I never managed to get comfortable with on the recorder, even over several years of playing. There are no half-whole fingerings (except for peculiar accidentals), and the transitions from a note to the note one step higher or lower on the staff is usually pretty intuitive.
On the whole, I’m having a blast.