What effect did Ritalin have on you?

I'm just inquisitive, as I was prescribed it about 5 years ago and hated it - insomnia, severe weight loss etc. I was so caught up in that, that I didn't really notice any benefits. I'm due to go to university soon and considering that I am ADHDp-i (predominantly inattentive), I was trying to see if it would be worth starting the prescription again.