It's hard to say from the description of "fairly standard". Libraries with C extensions may not work with JRuby. A few Rails deployment options aren't available with JRuby, and the ones that do support it may treat it like a second-class citizen.
In short, there's potential downsides that may or may not be relevant to your usage. That said, even if you aren't using the Java ecosystem, the garbage collection, performance, and threading in JRuby may be worth your time. It's all up to what you're actually doing.
In short, there's potential downsides that may or may not be relevant to your usage. That said, even if you aren't using the Java ecosystem, the garbage collection, performance, and threading in JRuby may be worth your time. It's all up to what you're actually doing.