You might wonder what possible use one might have for blu-ray quality when applied to cgi series, but in the case of Berserk there's at least one huge improvement -- naked women now have anatomically correct nipples, unlike the disturbing barbie dolls they were for tv. I suspect the lack of censorship allows for more gore and the like too. Since the actual Berserk manga was full of nudity (as was the original animated series), it's only right to upgrade to this version, cg or not, for the sake of fidelity. This is the real Berserk we all remember and love, or as close as we're going to get to it.
There's still no point in rewatching Berserk in blu-ray until the current season is also available in blu-ray, which might be another year from now, but it's always best to grab these torrents while they're hot. Who knows if they'll still be seeded a week from now.
Once they're done making new Berserk and it's all out in uncensored blu-ray, that will be the time for a nice marathon rewatch session, but for now it can sit tight and wait behind many more important priorities.