First, the Cliff's Notes version:
- Smite's 40 second cooldown inhibits counter-jungling and eases clearing for tanky junglers.
- Spirit of the Ancient Golem is still the best of the jungling items.
- Having two "small" camps on each side helps jungle flow considerably.
Smite's 40 second cooldown is a big deal. You no longer need to worry about saving Smite for your second buff because you can have it up for both. If you Smite your first buff on spawn it's seamless (though that should obviously only be done when you're certain it's safe). Even if you don't you can just take 10 seconds to look for the enemy jungler and Smite will be still be back in time to secure your second buff.
This makes contesting an opponent's second buff significantly more difficult early on. The types of junglers who routinely have their buffs contested tend to take extra time and damage at their first buff unless they get an extraordinary amount of help. Being able to Smite that first camp means a healthier jungler will arrive at their second camp sooner. Combined with every laner having the ability to throw down early wards, early counter-jungling is going to be rare except in very lopsided setups.
Having Smite up constantly also makes clearing much easier for junglers in general, though tanky junglers tend to benefit the most. All in all it's a huge quality of life change.
All the jungling items now have gold generation passives aimed at boosting jungler income. Of these passives, Spirit of the Ancient Golem's stands out as the most versatile for fairly straightforward reasons.
Conservation, the passive in question, stacks once per second up to 80 times. Killing a large or epic jungle monster consumes up to 40 stacks granting one gold per stack. The upshot of this is you can half a minute and a half of downtime without losing incoming. Moreover, you still gain roughly 10-15 gold per camp if you're straight up farming due to the time it takes to move between them and clear. With four small camps and a low cooldown on Smite it's easy to make use of the passive even into the late-game.
Bounty Hunter, the passive for Elder Lizard and Spectral Wraith, is considerably less potent. The 10 gold bonus per camp is functionally worse than Conservation. Getting two kills/assists every 80 seconds to keep up with the potential of Conservation is basically impossible except in low level games. At the moment I question the value of either Spectral Wraith or Elder Lizard.
The new Wriggle's is potentially powerful, although the much whispered about upgrade currently does not exist. If you're straight up farming the jungle Wriggle's provides a very considerable amount of gold. The problem is that Attack Speed, while sensible for Wriggle's passives, is not by itself that great for most farming junglers. Without the upgrade Wriggle's is a little awkward.
The new jungle camp makes a huge difference to jungle flow. Absolutely huge.
One of the biggest problems facing a jungler is balancing farming and ganking, and a large part of that problem is how their clears flow into their ganks. In Season 3 ganking the side lane closest to the wolves camp is the most costly in terms of time and farm. There's just the one camp on that side and it's fairly distant from the lane, especially if there are wards involved. It's still a gankable lane, the issue is simply that the personal cost to the jungler is higher.
The wight camp significantly helps this problem. It's positioned extremely close to the lane, allowing for quick access in case something happens. It's now easy to flow from wolves to wight to gank, or even vice versa. Moreover, if you exit the gank with a lot of health you can almost always go straight back into the jungle and have a nearby camp waiting for you. Jungling flows better in Season 4.
Overall I'm liking the new jungle, but there's a lot left to figure out. Double jungling might actually be viable with each jungler able to farm two camps. Dealing with free wards all over the map will be an interesting problem.
My only regret is that none of the jungling items are really suited for jungle Akali, alas.