Abraxas
Explorer
Only that now your DM can use enemies 2 or 3 levels lower which don´t hit as often but do more damage and less hp.
This will cause combats to be more exiting, because its not autohit with low damage. HP of monsters will be lower, so the fight will be over a little bit faster. You will just get some less xp. But this may also be not a bug, but a feature, since previously leveling up was extreme fast, when combats usually were level+1 or level+2...
Well, the people in the game I play in are casual gamers - Level+0 challenges already were challenging - now they are going to be murderous. The rules updates weren't made to account for those type of gamers. They were made for the gamers I have in the game I run. I expect the number of dead PCs will ramp up quickly.