First of all, I love the bedding that you used, which helps out a lot! I would look for curtains that pick up the beautiful blue in the bedding. That would help give the room some more color and life! I also suggest colorful kids art or photos for the wall above the beds. Here are some ideas:

Child Bedroom · More Info

Westwood Home · More Info

the other side of the room

I agree with what Bev said. The room is set up very nicely, now you just need to accessorize with artwork and pictures. You could probably change the curtains to something more along the line of the blue in the bedding, as well. I don't know if you've thought about getting a little night stand to go in between the beds. If you decide to, don't get the same color as the furniture.

Love everything you've done but you're right, the room lacks personality. I agree with above comments about bringing in some colorful art. Also, put another smaller pillow on the beds to bring in some color - I think orange would work well. Hang a shelf over each bed for books. I've used a vinyl decal on a nursery wall before - there are all kinds of them and they also help bring in color and personality. Below are some ideas.

Set of 2 White Distressed Wall Shelves · More Info

Coptic Pillow, Blue/Orange, 15" x 27" · More Info

Primary Colors Alphabet Tree Self-Stick Wall Accent Set · More Info

Paragon Global Contemporary Tangled Wall Art 7919 · More Info

Loved the shelves

I have done the shelves idea and changed the bedding into a brighter color and the room looks nicer and kids loves it