I could either go freelance or work for a design agency as a contractor, where I would get a greater variety of work and in the future the chance of greater pay, but with no perks or stability as with a full time position.
I could work for a design company and have the aforementioned perks and stability, but I might find the work might well be bland (following the house style) although this is not necessarily a rule. If, through experience and promotion, I might be in a position to change the house style then clearly this wouldn't be a concern at all.
Holidays are an issue if working freelance or as a contractor in a design agency, in that you would only get paid for days worked, and any time out from work is therefore lost money. This could be an advantage however in providing more flexibility to pursue a varied lifestyle, obtain further training and skills etc.
On the other hand I could work full time and get a holiday allowance (I believe this is 21 days, certainly this figure or higher seems common).
On a freelance or agency basis, you will be in a position to own the copyright to your own work which might lead to an income from royalties for successful work, and more notoriety.
In summary a freelancer or contractor offers the chance to obtain variety of work, and to fit this into a flexible lifestyle, with the possibility of good money if successful but at risk of financial security. A full time position would be safer, and has other attractions. As I'm considering a degree course as part of my plans for the future I feel it may be too early to answer this question, as I feel I still have much to learn and the job market may change significantly in the next few years.