I'd go along with Mendeleyev on this one. It's also VERY important to note that, in Russia, you do not always get same-price countrywide coverage through one provider as you do everywhere else. I use Beeline as the example here because it's the company I used on my last visit.
Russia is so huge that, for example (as I found out to my cost), one type of Beeline SIM card sold in Moscow will give you cheap rates only for Moscow calls (landline or mobile). Go somewhere else and your credit disappears in a big hurry. The fact that you can recharge the card anywhere tends to mask the fact that you're suddenly paying three or four times the amount for what you think are local calls under the same provider. You are now "roaming!" Apparently each city or region's Beeline is actually a separate company under the overall brand.
If you will be going to other cities make sure that the card you get is a flat-rate NATIONAL card, not a discounted one-city-only card. Unfortunately I had misunderstood the woman at the kiosk at Domodedovo and got the wrong type. I would point out that this kiosk is totally independent - they sell cards for all the networks, and it seemed that they really do try to find the best fit for where you're going.
As for Beeline's customer service, I went into their main store in St Petersburg, where a young man explained all this to me in flawless English. From my point of view I'm quite happy to stick with Beeline - next time I'll just take more care to get the right sort of card!
This doesn't apply to Ukraine, where I used MTS after consulting a fluent English speaker working in an independent shop in the central underground mall in Kyiv. Coverage for all networks is totally national.