Clearly ICU isn't for everybody. It is where you see the sickest patients. They're very labor intensive, and you often/usually can't interact with them much on a cognitive interactive level.
These rotations help clarify what your niche might be. Most of us don't fit well everywhere. I thought I might want to work NICU, until I did a 7 week rotation there during nursing school. It was tremendously interesting; but I also found it intimidating and emotionally hard. So that helped decide the issue for me.
Actually I enjoyed my second day of ICU, I think it depends on who is the nurse they pair you with. The one that they paired me with on the first day kind of made my day miserable.
Second day, the nurses asked me a lot of questions like what are my skills what do I know and tested my knowledge. Then they were like we need you to do this, this and this... Like they trusted me to do accuchecks etc etc.. Check vitals, so it was like I was a mini nurse... so to speak so that experience was amazing.