I did the opposite actually. I did adult ICU for years before I did PICU....huge learning curve for me...and I was pushing 60 at the time. (oh to be 60 again!). Later, I stared moonlighting in the NICU. Looking back over my career (I'm retired now) I would say PICU was the most satisfying place to work in all my years of nursing. NICU was a nice change of pace, but I don't think I could have spent my entire career there. If you love variety and learning something new everyday.... and seeing many of your patients get better (which I didn't get with adults)....you will love being an PICU nurse.
Best to you,