I like how easy it was to set up, configure & maintain this product across all my environments (Dev/Test /prod).
It's also very flexible when you want your solution architecture changes are not always straight forward or possible with other products out there in market place that do similar things as packers but can be more costly compared tooo others so worth considering! Nothing really at present although we have used some of its features which has been great - especially if using VMs where they make life easier than ever before by automating many tasks such us deploying new versions etc.,.