Whisper it, but Dr Zhivago is a difficult read in any translation. It may verge on sacrilege to say it, but it is profoundly flawed as a novel. It's a rambling, disjointed, episodic work. There is a huge jumble of characters, most with little back-stories, who you may need bear in mind for eventual reappearances, or may not. Some theoretically central characters, such as Zhivago's wife Tonya, are woefully under-drawn. There are many children present, but they have no presence. There are plot twists of Dickensian levels of improbability.
Dr Zhivago is a highly cerebral work, indeed it is probably a novel of ideas above all else (though it is also a chronical of an epoque, an era of social and moral collapse). Possibly as a consequence, the dialogue is at times breath-takingly clunky, unreal. You can't help thinking that Pasternak was not a listener. It may be different in Russain, but in English transaltion the prose often doesn't flow, though from time to time you will be stopped in your tracks by a lovely, evocative, poetic piece of description. Russian naming conventions are a problem for any Russian novel (and they are worse in one set in the Revolution, because of the additional stratum of 'noms de guerre'), but we can hardly blame Pasternak for that. On the other hand, a proper name index would be a blessing. And by proper index I mean, in the case of Dr Zhivago, an index several pages long, with page references; a necessity because so many minor characters make reappearances somewhere down the line. (A tall order, perhaps, but I think the publishers owe it to us poor readers as we struggle to differentiate narrative wheat from chaff).
Yet, for all its obvious difficulties, this is a work with a massive, world-class reputation. How can this be? Given the patent difficulties with the text, I can't help thinking that geo-politics is partly responsible; the West did so love a dissident voice during the Cold War. Pasternak also had a first class (Nobel standard) reputation as a poet. You may find that the novel's reputation is the main reason that you persevere. If I'm honest, it was for me. Even though the wait for the novel finally to come into its own, reveal itself, was ultimately a search for the end of a rainbow. The emotional climax is fleeting, and ended by another improbable plot twist. The conclusion is a great anti-climax. Even so, I am glad I persevered, because the novel does have its rewards, and lingers in the memory. But it was a big struggle (in a way that, for example, War and Peace, with which there are obvious parallels, is not)and I confess I did resent it, frequently. I can't help coming away with the abiding impression that this novel is a mess, albeit a mess with the best intentions, and its heart in the right place. Why is it such a mess? I suppose, first, it's a novel written by a poet and an intellectual - a different skill-set from the average novelist, though some can pull it off (for my money, Michael Ondaatje can). Secondly, it would have been utterly transformed by the firm hand of a good editor, which it evidently never received; good editors for politically controversial novels cannot have been thick on the ground in the USSR in the 1950's.
So, with all these difficulties, Dr Zhivago needs all the help it can possibly get from its English translator. Here is where you can improve your experience, and should tread with care. I strongly recommend you look at both translations before you buy - the original Hayward & Harari (a much looser, but more readable translation, though still frequently a struggle) and the recent Volokhonsky & Pevear (a much more literal, but more clumsy translation). I also suggest you read the article in the Guardian on 6th November 2010 by Ann Pasternak Slater, which extols the merits of the former over the latter, and gives specifics: see [...]. It is intriguing that the Volokhonsky & Pevear literalism which worked so well in their translation of War And Peace runs into such difficulty with Dr Zhivago.
Your choice could make all the difference between surviving the experience, or not.