We are a flexible packaging supplier registered to the IFS PACsecure standard. We have been registered since it was developed by PAC in Canada, and have continued through the process of benchmarking with IFS.
Overall, personally speaking, I find it useful. It is definitely targeted towards food packaging manufacturers (glass, metal, paperboard, flexibles), so the standards themselves are, for the most part, reasonable and useful. It has definitely helped us focus on GMP areas that ordinarily don't get enough attention (our business is split between food/medical, industrial and geomembrane environmental containment).
New (or relatively new) with the IFS benchmarking is a much greater emphasis on risk assessment, which can be a big hurdle if you're not used to that level of documentation. As mentioned, the annual full system audits are a bit of a drag (although our auditor is great).
It will be interesting to see how well it's adopted. I think there's only a relative handful of adopters in Canada so far, and a half-dozen or so in EU.