If I Was the Sunshine is one of those books where there is nothing wrong with it, yet it is also a YMMV book.
The text will be relatable on a personal level. You take away what you put into it. If you think it will be a lovely story like Guess How Much I Love You (a father/child relationship) it will be a lovely story about a parent/adult and child relationship). If you think it will be a sappy-pappy piece, then it will be a sappy piece that will be too sugary to stomach.
With that said, Julie Foglilano has written a quaint, sometimes a tad abstract story in rhyming text about a (assuming) parent, telling their beloved child a song-like story about how they are connected (if the parent were the sunshine the child would be the day). The narrator gives such examples as these:
if i was the sunshine
and you were the day
i’d call you hello!
and you’d call me stay
if you were the winter
and i was the spring
i’d call you whisper
and you’d call me sing…
Publisher recommended ages are four to eight. However, I would say you could go slightly younger as well. The size might be a little awkward for very small hands, but should lend itself for story time and everyone seeing the pages due to the larger size.
However, it was Loren Long’s illustrations that I got the most out of. They are cozy and bright. They have the colors needed to show the image (flowers, the bear sleeping under snow) and at the same time solid images. And while we have seen these kinds of illustrations before (they are reminiscent of people like Nancy Tillman), they are delightful to look at as you go along (however, I would have liked to have seen a fatter skunk and squirrel).