Sitting here, still using a Mac as a dev/everything machine. I know Lion is supposed to suck and all, but my 2010 MBA still gets insane battery life under OS X, the tool chain is top-notch (Clang, LLVM, etc), there have been a ton of improvements under the hood (TLS support being a big one), and I actually appreciate full-screen XCode or Emacs given the 13" screen. Even Xcode seems to, in 4.6, be getting back to the…
Not an OSX user, but many of the complaints seem to stem from Apples crusade on filesystems. For many (even not power users) this can lead to data loss; you open a file and sketch out some changes, and everything was magically written to the disk without you ever noticing so now you can't get the old data back.
You're able to get old data back now in a way that you couldn't before... and can't on other systems.
Whoever represented it as some sort of data loss was confused or lying.