The best thing I can say about the bf6 beta is that it runs pretty well. Maybe that's where all the effort went. People forget how unplayable some of these games have been even post-beta at launch.
Anyway, I'm 28 years old. My first Battlefield was 2142 and while I have a ton of nostalgia for it, I can see it's mostly JUST nostalgia that I have for it. I had to go out of my way to play 1942 and 2 with communities and with friends and am glad I did, because those games were really fun and I wish I had been able to get into them more when they were in the main spotlight. 2's expansion maps especially are just fantastic. On that note, it's odd how some games have significantly better post-launch support than others. BF1 came out super strong but never really took massive leaps with its expansion content. BFV meanwhile was pretty ass but made significant ground down the stretch towards the end.

It wouldn't be fair to rank a beta as a whole game but I'd say BF6 so far is a D-tier experience. With some fun big maps I could see the launch game maybe hitting C-tier, but there is still just so much wrong with the game. I can't deny it has somewhat of an addicting quality to it which is why I won't say it's "bad", but DICE has their work cut out for them to improve the game substantially post-launch.