I had the chance to play around with the new jungle last night and thought I'd go ahead and compile a few of my thoughts on it.
First of all, they were not kidding about the new jungle being more difficult. I'll get to the item changes in a second (because I believe that's what's driving this change) but one thing I noticed immediately was how much stronger the Wraiths/Razorbacks camp is compared to previous seasons. Buff camps spawning later was a bit strange to get used to again, definitely a throw back to S1/S2 with that particular change. Overall, the jungle reminds me a lot of S1 jungle.
I like the strategic diversity that each camp offers. Wolves/Razors give you a vision-oriented buff while the other set of camps give you combat related buffs. The execute damage has some interesting usefulness. You can quickly clear minion waves and small jungle camps with this bonus, so even though it's a combat related buff it gives you options with how you want to utilize it. I would say it is probably the most powerful buff at the moment, but I don't have a good feel for how strong the Ward-clearing buff from the Razors are yet. One thing to note is that different playstyles are going to favor different buffs and I think as the game goes on the importance of these buffs is kinda diminished.
The item changes... I both like and hate. I like that the items require Smite to build in the first place and that the stats you get when you upgrade them do seem nicer. However, what I don't care for is the lack of sustain on the new Machete and the base items. If this is an effort to make people think about whether they want to farm or gank, I'm not sure it's the best way to go about it. The Spirit Stone changes that gave meaningful sustain to a lot of champions really opened the door for champions like Wukong and Pantheon to have a role in the Jungle. Without that sustain, that role is going to be extremely difficult to impossible. I hate the Hp5 /Mp5 approach because it largely invisible power and frankly it's not enough at the current levels. (No seriously, try to jungle with Evelynn right now and you might clear 1 camp before having to recall.) I don't really know what the goal here is. With the new cost of the machete you only get 2 pots as opposed to 4. I couldn't clear either side of the jungle without first recalling to upgrade my Machete. I had the most success with Udyr, but now he has no mana regeneration early, which really hurts him (and again, that paltry Mp5 from the Machete is not really helpful). I couldn't clear the red side at all with Lee Sin. The Razors actually killed me (which as a bit of a shock tbh).
So it sounds as if the jungle is "more difficult" but I really take this with a mathematical approach. If your sustain from camp to camp is greater than the damage you receive, the jungle is considered "easy." If not, then it's "hard." That's not really the case though. Difficulty doesn't come from a static comparison of ins and outs of your health and mana. Making the jungle camps different with unique abilities and strategies to beat the monsters would make it "difficult." Kinda like how the new Baron requires you to react or you end up taking more damage than you should. That's the direction the jungle should go and then it would reward people who are better at executing the jungle (rather than just maximizing their damage).
I mentioned the smite changes so I thought I should also mention the smite upgrades as well. Right now, they seem to lack functional diversity. Destruction and Duelist are very similar, so it'll probably come down to which one is strongest in the meta as to whether one gets used or not. Champions with lots of mobility will probably favor Duelist, but I think Destruction is going to be more practical. Trailblazer is clearly a hard farmer's choice while Poachers is a counter Jungler's choice. Both are kinda meh to me though at this point.