It's not only safe, but a much nicer flight experience than some other Western European/US carriers. I used to fly SU from SVO-JFK routinely in the early 1990s, and even then the flight attendants were a lot nicer than Delta's on the same route. Last week, I took SU in business class to/from LHR, and they beat the pants off the BA flight in every department (seat comfort, fast/friendly service, IFE, for starters). And now, finally, you can get SkyTeam miles for traveling on SU!