I think I am the first person to play current elemental procession, so here are some thoughts!
Raid is pretty fun. The huge variety of bosses stops you really mapping out a full strategy before hand, and their actions and damage is sufficient to keep you on your toes.
I really like having a 4th pokemon, it makes a lot of things that would have been crippling in previous versions much more fixable by swapping out. For example if your Ag gets confused that sucks but you no longer have to stand still for 3 rounds.
The big backpacks are fun and help a lot with both winning the raid and giving turn by turn decisions.
However the raid suffers from a lot of the problems the previous version of safari had. There is a lot to keep track of with boss rules, type charts and stats changing every 2 rounds, and if you do a small math error (or typing error, rip razor wind into a ghost) you eat more than an entire round worth of additional enemy actions (because you eat dyanamax actions as well as their normal turn by turn.)
Melmetal is particularly scary here where if you do not 1 shot their partner pokemon he straight up kills a raider with an action that "shouldn't" have resolved.
It is a relevant point that raid lifelines are quite strong and can definitely help you counter a slip up, but yeah it was inducing the same kind of paranoia in me as safari did.
Re difficulty I think it looks like it is in a decent spot. You need a team that can do enough damage to 2 round most waves and has the defensive and utility tools to counter the bosses actions. Doing this and also bringing at least 1 pokemon who really wants the dynamax seems achievable and like victory will come down to your play within the run instead of being "auto" win or lose.
I think the easiest way to accidentally kill yourself in team select is if your ag is too fast. You really want to be moving slower than every boss you can except melmetal and you will eat a lot of nasty dynamax actions if you go too quickly. One thing I realised part way through my run is how pivotal razor wind was, I had not anticipated that a negative priority aoe would be so relevant, but even with -spE nature butterfree was still outspeeding things like grimmsnarl and lapras.
Ty
Ayush_1 for reffing! It definitely looked like a lot of work. Lots of profiles, lots of boss actions, lots of damage calculations that change every 2 rounds.