I had WP site for 2 years that's why I gathered the great bulk of material. Deciding on switching to Joomla I really worried about my wesbite, but CMS2CMS made the migration properly.
To be honest I didn't expect that procedure will be so fast. Also, this service has a lot of video tutorial that help with the migration. And what's more you may try demo for free before paying.
So, I recommend this app to everyone!