Ah, then!
I loved it! A lot. Though, my for all time favorite author is Dickens, I appreciated Thackeray's special bitter humor and his sharp look at life very much. So many times I have thought why do all these books end so happily, and smoothly, and logically (which according to real life is quite illogically and far from reality)? Many times I tрought why has there never existed a book where evil wins, where good is shown with all its drawbacks? So, The Vanity Fair (as a real piece of critical realism) was for ten steps closer to this my ideal: Nobody is perfect, but this makes us people. Both dark and bright colors; the way we love and betray; the way we show the generosity and then show cowardlyness, how we can actually be. People who are completely sunny or completely dull and stormy, windy and grey like rainy days are very rare. Most of us are changing, moody, like the day where clouds and wind close and then open again the sun constantly. None of Thackeray's heroes (I have read only one of his books) are perfect or однозначны, односторонни. Becky is sparking and beautiful, smart and witty, strong, she is a fruit, but she is a heartless mother and betraying wife. Amelia Sedley is sweet and tender, but, she is silly and simply a simpleton because she loves the wrong man and doesn't appreciate the love of the most generous man of her lifetime. And Dobbin is fair and generous and so loyal to all his principals of honor and love, but, even he understands (and too late) that he was stupid and lost his best years in vain in sake of the woman who does not deserve his love. Becky's husband is a natural fool, but he is a man of honor and bravery and he loves her truly and with endless loyalty.

But the more I see how fair and cynical the Life attends to the heroes in the book, then the more I felt how deeply I was attached to it's action. I feel how true is Thackeray. Life is the mixture of the salt and sugar and we are supposed to eat this blend until we die. When I think about wild animals which eat the flesh (wolves or lions) I think how much dull and similar is their daily meal without fire, salt and spices. But they have to eat it, tasteless, only tasting of blood. So are we. We have to eat what the life gives. Happiness and bitter of disappointments and grief, эйфория and pain of love, we have to feel the taste of our deeds. We betray our friends and make the new ones. We make our relatives feel beloved and unhappy. It's a life, it is the real taste of life. The man who is known as the most reasonable person of his gender makes the biggest stupidity. We are the причудливая mixture of virtues and sins (добродетелей и пороков). And we love it.

Nobody is perfect. Nobody is hopeless. We all are bad, we all are good. There is no winning without the loss and no good without bad. Our world - the human's world - is a vanity fair, colorful range of events. The greatest events which stood unseen and stupid events which turns on everyone's tongue.

He was very very true in his viewing of the life. Dickens can lie and hide the evident truth, he is an idealist. He is true but until some border where Thackeray stepped over this border. There are no more just good or just bad heroes. They all are good and bad.

Here is what I can tell in "English" (I would be more constructive talking in Russian though)

edited with help of the rockzmom. Thank you!