Our guild did a lot of prep work for Patch 4.1. Several of us got together before the patch went live and formed groups to clear Zul'Aman and Zul'Gurub. There were promises of new loot, new bosses, new mechanics and new features that were very exciting, especially for a "minor" content patch.
Upon logging in, however, we all immediately noticed several addons were broken or were breaking the game. Recount and Skada caused a lot of problems the first day, but so did Deadly Boss Mods, Bagnon, Mik's Scrolling Battle Text, and dozens of others, before they were updated later that evening.
For the most part, my main (a shadowpriest) was unaffected. I simply turned off Recount and kept rolling. None of my DoT timers needed fixing, and everything else was purely cosmetic or out-of-combat-oriented (although Bagnon got annoying after a while). My blood death knight, however, had major issues when my rune tracker wasn't working. It got to the point I couldn't play him, simply because I was so flustered with trying to track my runes using the native UI. All my plans for tanking dungeons for new mounts went right out the window; instead, I opted to try to make money enchanting for all the new gear that was just introduced.
When your favorite addons break, do you change your game plan for the day? Do your addons change how you play the game or your comfort levels with your characters?