+1 for STS3.0 on Eclipse 4.2 being unusable on OSX...
I think there is something wrong with e4.2 corrupting workspace metadata.
It seems I get about two start-ups with a workspace before STS3.0e4.2 can no longer get past "loading workbench" stage and I have to Force Quit STS. At that point my only option is to delete the workspace, recreate it blank and start reimporting projects (@!#$@#!%$#@).
When I first loaded up the workspace, I noticed it would always corrupt the metadata if I deleted a project from the newly created workspace and restarted, but it happens even when you don't delete any projects...
Anyway, I agree that the e4.2 release on OSX is putting STS in a terrible light, I would suggest pulling the release or replacing it with that e3.7 build.
@Lari thanks for the links to the e3.7 based build... I'm pulling down http://download.springsource.com/release/STS/3.0.0/dist/e3.7/spring-tool-suite-3.0.0.RELEASE-e3.7-macosx-cocoa-installer.dmg and I'm going to give that a try shortly.