Some friends and I were playing SR4 a while back, it was a little before the anniversary edition was released. After a long hiatus we are planning on trying to get it going again. I was flipping through the SR4A book at a store and it looked really nice, especially lovely was the index. Browsing the board it seems there were some rule changes in 4A. I was just wondering how significant the changes are (spell drain was the only biggie I could find). At least one friend had bought the 4th core rules, and if I get 4A I would let other friends borrow my core book. Just wanted to know we'd run into many "well that's not how it works based on what I read" situations. Maybe there is already a compiled list of rule differences so we'd all be on the same page (slight pun intended).

Anniversary edition = Non Anniversary Edition + Errata + Changes doc

All you need is the Shadowrun Changes Document at Errata

The other difference between the books is that the SR4A has extra fiction, so by the time you get to the combat chapters, you'll be adding 10 to the page number between books.

One of the other somewhat "big" change was that the Wireless World chapter got rewritten for the Anniversary edition. Now, it did not introduce any new rules as such the different presentation, and the clearer writing in the Anniversary edition may make it appear that the rules are different. If you have someone planning on playing a Matrix specialist character, I highly recommend they read the Wireless World chapter from SR4A.

I blame Aaron for all of the improvements to the Wireless World chapter.

Ignore those. The biggest change was the additional drain to direct combat spells, which is essentially optional, and has the inverse effect that the rule was intended to do (discourage overcasting).

Excellent, thanks for the replies. One of my friends does have a Hacker type, so I'll look forward to the rewritten Matrix chapter.

My biggest/best advice for you for running Matrix stuff is this: think of a computer system as an alternate physical world rather than a computer system. Think of patrolling IC as a patrolling guard rather than a computer program. Make it exciting, fast, and fun. Focus on what the player is there to do in the system.

Thanks Malachi. I remember reading your Three Data Monty sessions last time I was playing. I enjoyed reading the session reports, and seeing how you used the Matrix in your games was very helpful. Looks like you have a second one written up now, I'll have to read that next.

Extraction Reaction was a much more "action packed" session. There wasn't nearly as much sneaking and Matrix stuff, but it was still very fun to run.

The big changes:
Karma cost for increasing attributes raise
Karma Awards for games: raised
Optional rule for adding to drain for extra successes on Direct combat spells
Enchanting moved from Street Magic to Core book
costs for some adept powers(especially Improved Reflexes) reduced.

We've been playing with the 4A rules since they came out, and I've been using my regular rulebook. The only thing I can't look up in my book while we're playing is targeting modifiers.