This new jungle is pretty awful, these changes were not necessary to implement as the jungle was finally getting to the point where all junglers were viable at some level of gameplay. I more than likely will stop playing summoners rift until something changes to make it more fun and less complicated (it is clear competitive scene drove these changes while normals get shafted).
As for why the changes are bad:
Overcomplicated. As someone who has been playing for little more than a year now I finally got good enough to be a decent jungler with non meta champs. But of course all that progress is gone now which is very disheartening.
Dragon not giving gold and giving what very much appears to be an overpowered buff. Also, only grants that buff at 5 stacks of kills if I remember correct. This means that only a close game that lasts to the late game will see a team reach those 5 stacks, which of course will tip the game drastically in one team's favor, who will then probably grab baron with the power they got from dragon and become unstoppable. In games that are already losing, the winning team can secure 5 dragons early and it will effectively be game over with absolutely no way to counter play. For people saying strategy is important you sure goofed up big on this one.
Camps are too strong for non-sustain champs to clear well enough. Champs like Nautilus were already hard enough to play because how poorly they can defend against counter jungling attacks. Stealing a smite on red and attacking while you clear the camp is now a death penalty for a tanky jungler and will set them impossibly far behind.
Lee Sin is, once again, over powered for no reason thanks to jungle and smite changes. He needs some nerfs to SOMETHING.
Smiting champions? Are you high riot? This will lead to free kills on anyone with high damage ganks at early levels, snowballing lanes early. Nothing about smiting champions is a good idea. You can joke about smiting teemo all you like but eventually people will stop laughing and start realizing how frustratingly unfair it gives certain junglers huge kill potential on them.
Changes to MR are bad as many others are saying. AP ratios are very high and to give us such weak yet expensive null magic mantles is making it impossible to fight certain champions, especially mage assassins like Fizz or Katarina, depending on your pick.
By making the first clear so difficult you actually have hindered champions that were previously regarded as worse.
Congratulations on cementing certain champions that the LCS deems "good" into being the only truly viable champs.