I love the vector, very cute and sweet looking.
As for the background, I think it's over blurred.
There's a bird next to the tree and it's over blurred,
it shouldn't be since it's big and looks not that far away.
The water is nice, I think it's too flat like theres no depth
in it, maybe adding more color will help and more waves
behind them, Also keep in mind that the water being so high makes
them look like their at a deep end which I don't think the other two
girls would be standing if so.
Lowering the water might help as well, and for the splashes of water,
maybe looking at a reference might help since the splashes are too round
and bulky to be water, also their a solid blue which makes it look odd.
Try checking out some Aria scans for water,
that will help you plenty.
The sky is nice, great sun you made in the corner.
the part of the sky thats behind the girls is too dark to
me, try using a baby blue to really give it a summer feel ^^
I really hope my advice helps and I hope
I didn't sound mean <3
