Joe has a great summary of the varied reactions to Bachmann’s departure. This article from the Economist blog disuses what she actually did (hint: nothing):

But hollowness, alas, is Mrs Bachmann’s legacy. Her brief seven-year tenure in Congress has been heat without light. She has chaired neither a committee nor a subcommittee. Of the 58 bills she sponsored or co-sponsored, precisely one passed the full House: a repeal of the Affordable Care Act that has as much chance of becoming law as it does of becoming a kumquat. She has missed more than 10% of roll-call votes during her time in office: more than five times the congressional median. And the less said about her casual relationship with facts the better. She was anger, indignation and a thousand-watt smile—nothing more, and her departure is good news for Republicans. Futile rage helps nobody. Marco Rubio, Ted Cruz and Rand Paul are far better standard bearers for the tea-party movement than Mrs Bachmann and Steve King. They are legislators who appear to have an interest in legislating, and who seem to understand that believing the government is generally inefficient and power-hungry is no excuse for doing the job of governing badly. That is far more than can be said for Mrs Bachmann.