That is a marvelous and very pretty sweater!
Challenging differs from person to person: Right now, I'm working on Elizabeth Zimmerman's Baby Surprise Jacket. For me, it's been an easy knit _so far_ given that it's all in garter stitch, but it is knit all in one piece and has only two seams one at each shoulder. It folds up like origami into the cutest little thing I've seen in a very long time.
I'm almost done but the knitted work looks like a knitters nightmare of a topological map, and though almost finished I'm still not sure how it will fold up neatly into a sweater. That was what motivated me to make the thing...
It may be an entertaining and useful knit for you with wee bairn number three due soon.