As a big 4 consultant who has encountered a number of independent consultants in recent projects, he's my contribution for what its worth:
Work/Life- all the independents I have met have had a partner in a 'proper' job, offering some sort of security the mortgage will get paid. All have complained that they get'stuck' in assignments as they don't have the option of swopping off as you do in a big firm.
Respect.... Sometimes you find a senior exec that has gone independant, knows everyone in the industry, really has seen and done it all- they get lots of respect from everyone and do make a fortune. Occasionally you find someone relatively young and dynamic who is making waves on their own in a niche area- usually in marketing, comms etc. Usually, independents are middle managers who got made redundant and couldn't get back into the job market, and clients buy them because they are cheap and can do something specific e.g. SLAs for public sector TUPE, mapping IT networks for an outsourcing contract. Consultants from big firms are often brought in to manage them or oversee a process, and I'm afraid our response on discovering we have to manage an independent is often to groan and prepare to add to our list of amusing assignment related anecdotes about difficult people.
Good luck, and whatever you do, never hold a conversation with a big firm consultant that includes the phrase'I never wanted to work for one of the big firms'- it may be true, but we, and clients hear 'I couldn't get your job'...