Pros
As a consultant (so-called "Employenuer") you get to experience various clients and projects who need a person in your profile. You are the only asset of the company, hence they must keep you happy, develop your skills as much as possible, and ensure that you keep learning in addition to the value that you add to the client.
Cons
The experience of working at TMC is strongly dependent on the quality of your Business Manager (who's in charge of finding new positions and keep up with your feeling at work). If the business manager is not competent, there's a chance that you feel like "just a number". If you are into staying in one company and going up through the hierarchy year after year, consultancy is going to be difficult since you keep moving from one to another client and you don't "build-up" your reputation past a certain point at each company. When finding a new client after ending your current project, you might have to compromise a bit since TMC isn't connected to the whole job market, you will be limited to the clients of TMC (though it can be a broad range).