I have no direct experience with the .338 Lapua, other than a couple of years ago I was toying with the idea of getting something chambered up for either that round or the .300 WM. But then I started looking at all the costs involved, after already having gotten into .50 BMG, and I ended up moving on to the next "gee I'd like to have X" moment. If I were more of a hardcore long range match shooter I might consider it, but even then there are still some pretty amazing things you can do with the .50 BMG loads at 1000 yards when needed. The .50 BMG might not be as accurate as the .338 Lapua, but its effective range is a lot greater (.338 Lapua can kill a deer out to 1800 yards, while the .50 BMG can reach out to 3300 yards to do the same thing) and... well... there's just something really super cool about having a .50 BMG rifle. .50 Browning MFing MG, man!
Since I know I'm not interested in long range precision competition, I think I would only get into .338 Lapua if I had more money than sense and had nothing better to spend it on.
Cheers,
~ Greg ~