I mostly agree. They added more strategy to the jungle with smite bonuses, and more diversity with the Hunter's Machete upgrades and enchants, but the sheer difficulty of the jungle has crowded out some junglers cough Eve cough and made everyone else feel like it's just not as rewarding as laning (and it kind of isn't.)
You would think that double smite would help solve this, but it seems like all that really did was make assassin junglers feel better about the fact that they're supposed to use their smites on players instead of camps now. It doesn't really help that much with clear times at all. Especially early game when it matters.
I think another problem is that in the old jungle, some champions had kits that just worked for them as a jungler, so they could jungle "right out of the box" so to speak. Now if you want to jungle you HAVE to create a rune page and mastery page for it. Yeah it was always a good idea to do this, but now it's completely mandatory and I think lots of people were using hybrid rune/mastery pages so that their champion wasn't "locked-in" to jungling so to speak. Like, maybe I don't like jungling, but I own Shyvana whom I usually take top, and I get in a normal blind or normal draft game where I get forced into jungling. Well my normal Shyvana runes/masteries used to cut it in the jungle, now they don't, so the one time I try it I die to Gromp or something and ragequit jungling for the rest of my time playing LoL. Situations like that.
Honestly, someone said it already, the biggest single problem is that sustain isn't there anymore. But I think the real reason for this isn't just that the creeps are tougher. Hunter's Machete costs 400 gold now which means you can only take 2 pots. Even the ability to take just a 3rd pot would change the perception of the jungle's difficulty massively. All they'd have to do is reduce Hunter's Machete's cost by what? 15 - 20 gold? Hell they could even add that in to the cost of the T2 upgrade as long as it let me buy a 3rd pot at the start, it'd be a worthwhile trade.