I got one in December and just replaced the batteries a few days ago. It's under pretty heavy daily use. I use Energizer Lithium batteries in my keyboards & mice.
My old wireless A1016 model (the white keyboard that uses 4 batteries) goes through them a little faster I think. Tough to say because it uses 4 batteries instead of 2 and I don't use it as heavily besides, but I think the newer one would use fewer batteries over a year's time with equivalent usage.
At one point they released a wireless keyboard firmware update to deal with battery life issues. So whatever the earlier issue was, I'd say it's fixed. My experience is that the battery life isn't as long as Logitech keyboards I've owned, but it's not egregiously bad.