There was a significant group of vocal "Apple Users" who have spent a great deal of time over the last couple of years slagging off WP and Android for "bad design" and "stealing". It's to be expected that when Apple borrowed so heavily from WP and Android in this release that there are going to be strong reactions.

It's perfectly normal for companies to be inspired by eachother and to incorporate the best elements of rival platforms (and Apple have done a good job in many respects, particularly the default apps), but Apple's litigation and the comments of the most vocal Apple supporters meant that they really have invited this backlash.