Yet another program tutor for Shapers. If Test Run and SMC didn't exist, this would be phenomenal, but they do, so it's only decent.
Looking at the card by it's own merits, it's excellent. It's installing a program for the action spent to play the event, and gets a potential discount when running R&D. The tag will probably be removed, since most Shaper decks I see have no desire to be or stay tagged.
Now I'll compare the card to the other Shaper tutors. Compared it SMC, this card is far worse, solely because it isn't instant speed. This will not replace SMC in any deck.
Secondly, this is better or worse than Test Run depending on the kind of deck you're playing. If you get a benefit from having a card out for a turn, like one would with D4d1v or Cerberus "Lady," or you Scavenge plus expensive programs to combo it with, Test Run is the better choice. Otherwise, Code Siphon is usually more effective.
Lastly, if you run enough "Toolbox" programs (x1 copies of situational programs to tutor for), or programs essential to your deck's strategy (like Keyhole or Magnum Opus), then it's fine to run all three tutoring cards. It might be a bit too much for the majority of decks, but it'll definitely be good for certain decks.
Overall, Code Siphon is a great card but to some extent overshadowed by the other tutors. Expect it to see some play, but not impact the meta much.