That Polish reader goes too far, but there are certainly aspects of the way the Polish were treated that those of the time ought to feel unimpressed by. At Russia's request, many of the Eastern European nations who fought for the Allies, especially the Poles, were excluded from the celebrations and various marches. And in particular during the Battle of Britain and, yes, the Enigma code, the Polish contribution was immense.
It's something of a shame that, for example, Marian Rejewski's contribution to cracking Enigma has been rather overlooked, in favour in particular of Alan Turing (although even his role is a recent "discovery", since the whole thing was suppressed as a military secret for decades). But the absence of Polish pilots from the VE-day celebrations was a shameful attempt to appease the Soviets.
See, for example, this article:
http://www.telegraph.co.uk/history/world-war-two/9594403/Poles-launch-campaign-for-Enigma-code-breaking-recognition.html
On another historical note, while the War may have started after the Invasion of Poland, it took the full length for Poland to be "liberated" -- and then fall under the control of Russia. I don't know if there's much we could have done to change this, but to chastise the Poles for showing lack of gratitude seems a bit mean. The Allies of the West (France, Britain) never liberated Poland. So what, exactly, should they thank us for?