Even though Reaper rivals the much more expensive digital audio workstation, Pro Tools, making the leap from Pro Tools to Reaper was not as simple as it might sound. Long-time Pro Tools users often get used to using the proprietary plugins (effects and virtual instruments). Pro Tools used a format called RTAS exclusively for most of its existence. But some plugin providers are now creating VST (Windows) and AU (Mac) versions of their plugins, which is awesome because Reaper uses those formats.
One example of a plugin provider who has done this is AIR Music Technology with their AIR Creative FX Collection. Below is a video from the Reaper Blog reviewing these effects in Reaper: