From what I've heard on the forums, its still working, and usable to this day. The author only updates it when things need to be updated as he's quoted, "if it aint broke, don't fix it".

I personally use ISBoxer since its functionality offers allot more than any program available on the market. If you like simplicity in a program, use Keyclone, If you want more out of your multiboxing, then watch videos, ask for a trial from lax, and check out ISBoxer. Its updated very near weekly, with interresting new features, tweaks on existing features, and intelligent control over jamba, teams, and keymapping. Repeater reagions use an area of the screen to copy mouse positioning for ease of healing, buff bar, mounting, hearthing, and more, no more binding a bar to a key to activate, since all you do is click.

Its all a matter of what you want to do. I rave it, others rave it, and not many have an argument against it.