Even though it comes with a lot of cool plugins, you won’t have fancy UIs, analog emulations or powerful instruments.
No 3rd party plugins are included with REAPER.
The way I see it, you can buy your favorite plugins with the money you saved when choosing REAPER. Instead of having tons of bundled plugins you pay for but never use, you have the choice of your tools.
There are the JS effects as well, some of them are really good but they usually don't have any UI