I've read 140 pages and couldn't stand it anymore. (Spoilers ahead! But only as far as page 140.)
The main character Tatiana annoyed the hell out of me (I could not stand Tatiana sitting there licking ice cream in her summer dress instead of buying food, because Germany had declared war on Russia the same day and her family had sent her to buy food. I really thought she was utterly stupid.). I also could not stand the overly perfectness of the male hero who's an American (!), but is an officer in the Red Army (!) and walks through Leningrad with Tatiana every evening for three weeks and openly talks about surely forbidden topics, like ... ehm ... the Russian Government wasn't really ... ehm 'fair' (remember, the Germans had declared war on Russia and the Russian leader was Stalin).
I also disliked the "Insta-Love". They see, they fall for each other and behave like idiots instead of just talking (i. e. excessive sitting in busses and staring).
And I surely could not tolerate that this guy was dating her sister at the same time. That he visits the family and sees Tatiana and her sister but plays the role of the sisters lover. WTF? Why does her sister never notice the glances, the tension? Because literally Tatiana and Alexander are eying each other all the time.
And at last I did not like how Tatiana adored him anyway. Adored everything he did! And sacrificed this supercool love because "she had only one sister" and would never hurt her.
Stop - the last wasn't the last. The last annoyance was the writing style. I thought it was cheesy: too many short sentences, too many sentences with a "She, He, It" at the beginning, too many short paragraphs, too many turns in paragraphs. Too dry.
Maybe I just did not get the point (I am not really the regular romance reader ;-) ), maybe I gave up to early. I don't mind. I just didn't like it enough to read further.