This doesn't wipe all your data, pics etc. According to Facebook this is in case you want to come back.
There's no definitive answer on whether Facebook keeps data you've previously removed but I would trash your pages before leaving.
In my experience, where they wiped a section (because I didn't choose to let them link it to dozens of Facebook pages on the same subjects) they still send me ads relating to those subjects.
Where I've set high privacy levels on family photos, Facebook merrily shows me that it's been mining those pictures, when randomly inviting me to tag them. Clearly their idea of privacy and mine are pretty different.
I'm afraid Facebook is extremely intrusive and has no regard for your rights. You are probably best out of it even if the best you can expect is damage limitation at this stage.