Sorry for the wordy reply, but I thought I should be thurough :
I've had a "new" card for several years and visit doctors and pharmacists on a regular basis. Please note that even if a doctor or pharmacist is equipped with a computer and system to read the card, this does not neccessarily updated the card for everything that might need updating.This can be quite troublesome If you have a medical emergency, or have to see a different dr during your doc's holidays. You may encounter trouble with your reimbursements.
I would recommend the following : Print up an "Attestation de droits" at the Secu at least once a year. When you use one of the free access machines to do this, it will automatically update your card, AND the attestation will tell you what your current status is.
3 very important bits of information appear on that paper : 1)the name of the other family members covered, 2) your "organisme de rattachement" (office you depend on), and 3) whether or not you have a "medecin traitant".
1) I'm assuming that if you have children they appear here. There might be spelling errors or an error in their social security number that you wouldn't pick up otherwise. And trust me, this might cause probs later on!
2) Believe it or not, your organisme de rattachement can change without your knowledge! Mine changed a couple years after I moved to a different section of town and I was never informed. If you ever have a work-related accident, go on sick-leave, maternity leave, or request a reimbursement, you are supposed to fill out papers that ask for the organisme de rattachement's number, and you often have to send the letter to that "organisme de rattachement" which means the address changes if the number changes! If you see a change in that number from one year to another, ask for the full address at the help desk, otherwise your mail may never get to the right place and you'll be left with a financial and administrative nightmare. Likewise, make sure you fill in the right number, otherwise they might use it as grounds not to reimburse or they'll send the paper back to you saying there is an error.
3) The French Social Security now requires that each person choose a reference doctor. Your choice of a personal or family doc must be officially registered with the SECU. This can be a "generaliste" or a specialist such as a cardiologist. In any case, if your Attestation de Droits does not say "a déclaré un médecin traitant" under your name, part of your reimbursements will be held back under the pretexte you have not registered a doc. You and the chosen doctor needs to fill-in a "declaration" sheet (if they don't have one, you can print one up from the SECU machines or ask for one at the desk). You then need to send this to your "organisme de rattachement". Check every once in a while until it appears as registered/déclaré. PLEASE NOTE - if you change docs, it is important to check at the SECU office what the name of the declared doc is. I had to make 5 trips back and forth with newly signed declarations before the SECU took the change into account, and each time I consulted the "New" one, they held back a few euros on my reimbursements.
Remember, it's always better to be safe then sorry!