I, also having endured hundreds of children's movies in the past, consider this to be one of the worst I have ever seen.
1) I resent in this day and age having to explain to my children that Russia is not "the bad guys". Also, that mocking Russian names like "Poopchev" is inappropriate.
2) The grandfather fly's birthday party scene contained a quasi-sexist joke in which he implied that males drink beer and women talk on the phone. Two other flies also needlessly use the word "crap" twice.
3) The whole movie largely smacks of 1950's stereotypes and propaganda that I thought we, as a nation, were proud to have risen above.
In all it's just crude, badly animated, even more badly written and not worth wasting the time to view.