Yes but it does work natively and there aren't a lot of 32bit only plugins left. I have quite a few now, and all the major companies are now 64bit compatible. My only complaint is the GUI is sometimes not reactive but as I said I don't see 32 bit plugins anymore.
EDIT : and to clarify, the reaper bridge is automatic, no installation requirement, it's all transparent. If a pluging is 32bit and you are using Reaper64, it will open it in a different instance (you will have a window that is not embed in the reaper window), it's a bit messier, but it's stable and works well.