(Core Set perspective)
This is one of the few cards where you immediately realise how good it is. Even with only a couple of games played you'll get this into your hand and try to hide the grin at the (likely) unopposed runs you're about to make. That said, there are a couple of mistakes I made when first using this card that seem to be quite common:
The first is a rules issue: The you spend on this means you cannot use other 'make a run' events at the same time. That means no sneaky siphoning, you need to earn that one the hard way.
The second is a question of timing: At first I'd get this and put it down as soon as I had it. I didn't think about what effect this would have, it'd be good no matter what. That was silly of me. In my experience since then, there seem to be two ideal scenarios to play this.
Operation Twizzling Fist - Plonk it down as early as you can, before things really get started. Make the corp see the danger, make them sweat, make them react, then wait. Maybe you'll never do anything, but you might (ohh, you might). Now they have another server to think about, one they weren't planning on defending very hard, but now they have to (or do they?) Keep that twizzle going for a while and more often than not, they'll spread themselves out thinner than they'd normally feel comfortable. Then when they've given in to the pressure and ICE'd up archives, lower your fist and carry on as normal. Suckers.
Operation Oh-My-God-I'm-Pissing-Blood - Hold it back as long as you can, wailing on HQ from the front with a flurry of increasingly vicious attacks. Get them on the back foot. Get them to put their dukes up right an proper, get them protecting that precious corporate face of theirs with everything they can muster. Then install this and truck 'em in the kidneys.