Actually, I have never been there in April, I have experienced Paris twice, in winter. The first time was in January 1991, during the first Gulf War. The second time was for Christmas in about 2004.
The city is delightful in winter, the weather is moderate, not warm, but not cold and snowy (a disappointment the first time I was there, I was living in Florida at the time.)
I am read to go back.