I found an answer to this elsewhere, and thought you would most certainly be aware of it, but thought I would post anyway.
This plugin doesn't work in a multisite environment if you "Network Activate" it. Instead, you must go into each and every site and activate it and then go thru the motion of adding the redirect rules.
Could this plugin be updated to reflect what's required for multi-site?
What would be of greater benefit is that if you could have this available in the network admin, whereby you could create rules based on named variables "BLOG_URL" for one. Basically, I would like all my administrators to go to wp-admin, but everyone else can go to the homepage, therefore create a rule in the network area to "SITE_URL/wp-admin" for administrators and "BLOG_URL" for everyone else.
I tried playing with the wp variables, but couldn't get them to work. Does this plugin support that?