I have to speak up, especially when it comes to such an iconic classic. The newer version may be lovely and pleasant enough, but by no means is it even a shadow of the scent created for Audrey Hepburn. I have smelt them side by side. Along with the re-issues of Le De, Givenchy III, and the others. All very pleasant, all much different from the originals.
You may not like to hear about reformulations, nor purchase them (mainly I feel for a fear of obtaining old/off/musty/stale scents) but truth be told, there are many perfectly preserved vintage scents out there to be found.
As you continue on your journey in the land of fragrance you will [hopefully] find yourself experiencing (or wanting to experience) the original formulations of classic scents and it will change your perceptions of these scents.
As far as No 5 goes, it sells just because of its name, trust me on this I worked in the "industry" for a VERY long time and have experienced this firsthand many times.
Do try to open yourself up to experiencing some of the vintage scents, you will be pleasantly surprised.