I think a lot of folks should read that reversal and think about what not reversing it would mean in terms of precedent.
"In that regard, the Court of Justice noted that the General Court, like the Commission, had relied on the assumption that the fidelity rebates granted by an undertaking in a dominant position were by their very nature capable of restricting competition, with the result that it was not necessary to analyse all the circumstances of the case or to carry out an as-efficient-competitor (‘AEC’) test. 6 "
If the original ruling stood, then if you are in a dominant market position, you can't give rebates at all in the EU because doing so would automatically mean you are engaging in anti-competitive behavior.
Fortunately that is not the standard, and since the standard was never applied by court or the EC, hence they reversed the ruling.