We went in March and enjoyed it very much. We did a tour of the island, staying in different hotels every couple of days . On the North coast it was very quiet and we were able to have lovely walks along the levadas with practically no one there. The temperature was pleasant, neither hot nor cold.
It was quite a bit warmer on the south coast and Funchal was quite busy . I don't know how old you are, but we thought that Funchal was pretty well full of oldies, zimmers at dawn for the breakfast buffet, so if you are younger, I'd give Funchal a miss.
We did hire a car and drove round the island. It was really hairy sometimes with all those very steep roads and hairpin bends, but we survived to tell the tales.
The people are lovely and the gardens splendid.
Have a nice time.