Notes:

Rolls had already been nerfed in a previous patch (in the same manner – one less ending i-frame), but now back rolls have been nerfed even further, likely due to the sheer abuse of them online in conjunction with how difficult it can be to punish them due to input lag. It's good for offline just as well, however, as rolling was still an overly-safe option most of the time. Air dodges having one less ending i-frame is also a god-send for the same reasons.

Now, as far as shields go, we got a change nobody saw coming: an increase in shieldstun. Shieldstun is something that wasn't very effective in Smash 4 prior to this patch, as it was barely higher than it was in Brawl, meaning it was barely present, especially when compared to Melee & (even more so) SSB64. This led to many attacks being unsafe on shield due to characters being able act out of shields so quickly, as well as making shield pressure not as potent as it should have been (regardless of the fact that shield breaks are more common in Smash 4 due to shields no longer taking reduced damage). This change alleviates these issues, however, as Smash 4 now has MORE shieldstun than Melee. Perfect shielding will additionally be more important than ever now as a result of all this. I guess as a means to not nerf shields too much, however, shield damage on get-up attacks has been reduced.