There's lots to like about the 300 Norma. If you are choosing a new barrel, or build, or rechamber, and into the big magnum stuff, this should definitely be on your list in my opinion.
I've ran one now for a couple months and love it compared to my 338. It's a very easy caliber to shoot, noticeable less recoil then the 338LM, and seems inherently more accurate. And shooting Berger 215 Hybrids at over 3100fps, means a super flat trajectory at long distance. I haven't gone back to shooting my 338 once since I got this. Seriously thinking of selling all my Lapua brass and bullets and does and I don't see myself going back to it.
For reloaders, it seems to have a really forgiving range too, hard to find a bullet it doesn't shoot well. Have shot 208 AMAX, Berger 215 and 230s, and all were very accurate with Re33. The Norma brass seems quite good too. (And a little bit cheaper per round to load then the 338).
And now we are starting to see a couple manufacturers offering loaded ammo for this caliber, so it looks like it's here to stay.