Standing room?

So I’ve been to the juice box a lot but never tried standing room. I’ve also never been to a playoff game.

How bad is SRO during a playoff game?

Will I have sore legs and back after 6 hours of standing while not being able to see the game?

Or will it be a great experience where there’s room to lean and see the game?

Also how easy is it to be the opportunistic fan who poaches seats as the game goes on in playoff games?