It seems to me like the people who praise the Soviet Union, and the people who hate it were probably in the same social class during the time they lived there and probably lived similar lifestyles.
As a secondary question, why was the soviet union so demonized in western Europe and the USA, but praised in many areas of Asia and Eastern Europe (And remains the same way today)? I grew up in the USA, so I have a pretty biased and ignorant education on this matter.
People demonize it because the Soviet Union is (rightly) associated with many injustices that occurred there, including the forced labor camps, forced deportations, show trials and executions, as well as the oppressive nature of the totalitarian Communist regime in general. I think it would be a bit redundant for me to go into all the injustices that took place there as you can easily find them if you do a search on this subreddit or anywhere else on the web.
I'm not really sure where people praise it so I would ask to see evidence of that. However I can understand why people might be defensive about others demonizing the USSR. After all it was a homeland for hundreds of millions of people. It was a place were those people were born, grew up, and lived all of their lives. For better or for worse, people tend to defend a country in which they live because it is their country. Also, while the Soviet regime was in many cases oppressive, it does not mean that it was impossible to have a good life there. In fact, the standard of living for the majority of the people there had improved considerably over the decades. People got access many economic opportunities, free education, free healthcare, generous retirement benefits, ample vacation time, free summer camps for kids, and so on. It should also be pointed out that many of the terrible things that occurred in the USSR were limited only to the Stalin era and ended shortly after Stalin died in, in mid 1950's. Labor camps were dismantled, people who were deported were allowed to return home, purges ceased. Not to say that the USSR was some kind of a liberal democracy but, at the same time, unless you were openly political and chose to criticize the state, the chances of you getting in trouble were low.
In short, the Soviet Union was a huge country. Some people were victims of oppression or had friends or relatives who suffered greatly at the hands of the Soviet state. Others, on the other hand, lived fairly ordinary lives - they grew up, had friends/boyfriends/girlfriends, they got married, had kids, went to work, had vacations and so on. Not everyone experienced the same thing.