It’s all explained here:
If you want a video explanation:
If you want a text explanation I posted one on reddit and I honestly don’t have the courage to do the tables again here since I don’t know how it works on this forum, so:
In my opinion, it is exciting – less attritional, and we are likely to see some very good games in the pool stage already. H&A QF are fantastic, and now the “best 2nd” shenanigans that often boiled down to how hard your initial pool was will disappear.
For the record, next season, Toulouse will be Tier 4 from Top 14, so likely to face Leinster or Exeter in the pool stages.