A killer with a pump cost of 1 for +1 strength ! Woo !
Then comes the breaking cost : 2 per subroutine.
As anyone who has ever give this a try (or Peacock or Aurora) can tell you, it's just a pain in the ass. Multi-sub sentries are quite common, and all in all, it's preferable to spent 2 for +1 strength and 1 per sub than the opposite (and then, this option is not much appreciated either).
Add the cost of 5 to install, and Creeper keeps crawling in your binder. Its only merits is to keep the "sentry problem" hard to solve, which is a nice challenge for Runners after all.