Actually, nio_gets() just calls nio_fgets() with a size argument of 100, so it's not insecure if you have a buffer of at least 100 chars, but it doesn't work like the gets function in older C standards.
If your buffer is smaller than 100 chars, you must use nio_fgets unless you want buffer overflows.
Another feature request: add nio_scanf() and nio_fscanf(). (Unfortunately, these will have to be implemented as macros, because there is no vsscanf syscall, only sscanf.)