This is one of the best Duty Free shops I had been to in Canada (not that I have been to that many). Unfortunately, I do not go this way any longer as traffic at the Lewiston-Queenston bridge has been terrible since around 2007 when the Canadian dollar hit parity. I now travel the Rainbow Bridge and, frankly, the Duty Free shop in Niagara Falls is not as good.
Crossed through that checkpoint many times before traffic finally got so bad I started using the Rainbow Bridge. My funniest experience happened when I finally got to the guard and a sudden cloudburst hit. Just as the guard was about to say something, I said "I've arrived just in time for the rainy season". He had a good laugh at that, asked me some quick questions and we were on our way. One of the most amusing stops I had there.