Elba Island

Have not been on the island but to the vicinity. To, pro and con would be the same--in April, it could be quiet, too cool for swimming.
Probably best with a car.

Below is the official tourism website but there are plenty more resources you can find online.
http://www.visitelba.co.uk

I’ve been to Elba only in Summer and only with a car (which is a must because bus service is limited especially off season).

Although there are Napoleon’s exile houses to visit (now museums) It’s a primarily a beach/scuba diving destination. The island is beautiful year around but April may be too early to enjoy its full potential.

We are planning on having a car, any problems with taking rental car on the ferry?

I haven't been but know others who were quite enthusiastic about their travels in Elba.

Check the rental car contract. Some rental companies’ agreements forbid taking rental cars aboard ferry boats. Europcar requires prior approval for taking a car on a ship, unless it’s a regular ferry line for an Italian island, in which case it is permitted. I don’t know about other rental companies.

Very helpful, thank you

I took the ferry back and forth from Sardinia to Corsica with a rental from Europcar. They assured me that they had no objection to doing this.

I haven't been to Elba but it's on the list. My friends insist that it is the most beautiful place in Italy and go there every vacation.