Major patches break addons. It happens every time a major patch is released.
The good thing that comes from complete UI destruction is that it becomes a good opportunity to take a look at your layout and either replace broken or out-of-date addons, or redesign from the ground up.
After patch 4.0.1, I decided not to go for the complete redesign approach because I like the way my UI looks at the moment. Instead, I just took a look at the broken and out-of-development addons to see if there were replacements that could improve things.
Things that just worked
I was happy to discover that by the time I was able to log in a couple of days after the patch, most of the addons I was using had been updated. Among these were Pitbull (raid frames), Mapster, Chinchilla, Clique (shiny new version!), Grid, Opie, Power Auras Classic (although a few needed tweaking), Decursive, Bagnon, Postal, Quartz, Omen, Skada... plus many more. Yeah, I'm an addon junkie.
Things that worked... eventually
Beru that I found out that the big "Download" at the top of the WowAce window downloads the latest release version, not the Alpha version. The Alphas are listed further down on the right side of the page, with an 'A' next to the build number. After installing the latest Alpha, it worked like a charm! Incidentally, I believe the current release version should now work correctly.
Elkano's Buff Bars
Satrina Buff Frames to try out instead, but I did miss Elkano's. I checked WowAce on a whim the other night to find Elkano's had been updated, and now it seems that the errors have been ironed out.
I went for a week or so not posting any auctions and missing the Big Glyph Runout of 2010 because I couldn't face posting auctions with the default Auction House window. It wasn't until several days later I heard that Auctioneer had been updated and I was able to pick up a small share of the spoils.
GnomeWorks, a new project still in the Alpha stage of development with a lot of the features Skillet has, but I've since discovered that Skillet has been taken over by someone else and updated so I'll save comparing the two addons for a future post.
Things that were broken or out of development
Fubar - replaced with ChocolateBar + Broker plugins
I loved Fubar, but it has been out of development for some time now. With this latest patch several of the Fubar addons weren't fixed and I thought it might be a good opportunity to try to move to Broker again. Broker works the same way as Fubar in that you choose a basic addon for display (I went for ChocolateBar), then the Broker addons plug into that. I was able to replace all of my Fubar addons with their Broker equivalents including Clock, Performance, Friends/Guild, Garbage, Currency and Durability.
CowTip - replaced with TipTac
GearScoreLite broke with the patch and I really haven't got the heart to replace it with the full version.
Most hilarious new find
GnomeLicker - Records the number of Gnomes you have /licked. The World (of Warcraft) needs more addons like this.