There were a few major changes between 3e and 3.5 see the ranger class. I was wondering if there was anything that drastic.
The cost change to Attributes is pretty drastic if your converting from 4e to 4eA, direct combat spells, the bow limitation (especially if you were a Troll), and I think there was one that I'm forgetting.
The cap to dice pools, which, like the change to direct spell drain, is an
optional rule. Honestly, it was very annoying for people who had to switch from SR4 to SR4A, because the changes to Attribute costs messed up character advancement, karmagen was in limbo for a long time, and a few other changes (such as being able to only upgrade things like commlinks by 2 points) necessitated changes in existing characters.
But from the perspective of someone
starting out with SR4A, the differences are probably not as noticeable.