Leveling is definitely nerfed and I don't know why.
I'm a casual player, not a total noob but not far either, with limited experience with MXL from previous patches, and I play SSF/SP. While I had a smooth 1-115 experience with pretty much anything I tried in 1.8, I had a much rougher leveling in 2.0. Harder enemies (some of them pretty nasty, mostly the new ones), nerfed gem and rune usage, changes to classes and skills, less runeword options for early game, mana issues, perhaps worse drop rates(?)...all of it combined made this patch less enjoyable.
Some may disagree but I'm discussing this from a perspective of someone inexperienced who doesn't know all the ways to circumvent these issues.
I tried few classes and builds and this is my experience with them:
1. Totem Necro - seems to be FotM but I found it clunky early on and dropped it pretty fast. Also, I swear I have no idea what is the cold totem targeting and how, I found the lightning one to be more consistant. I think I'll try a Summon Necro instead...
2. Bloodzon - the worst experience I've had. Targeting of the skill is so wonky and annoying, half of the time I didn't know what it will hit, I was just wasting mana...it was bad.
3. Melee Sorceress - it was...ok. Not that fast nor easy, being limited with weapons doesn't help, I had to spend a bunch of money on gambling and oils and use arcane crystals to make the TU sword and Sorc chest. After that it was better but still not that smooth. Might try Cold Sorc next...
Now, my current favorite, Spearzon. Many don't seem to like it but I had a very smooth leveling to 107 with it. I used rare spears in most of the Normal diff and it was ok, you just have to keep Fury active (more on that later). I had a lucky drop in the form of TU Maiden Spear and it really picked up from there. The boost to move/attack speed and defense that Fury gives with healing provided to my main skill (Great Hunt), combined with damage and phys res from Fend, damage + AR + defense from Lioness, move speed, FHR, more defense and slow from passives made it a very fast moving and attacking build with a lot of damage and tankyness. I facetanked Diablo in Nightmare, but wanted to rip my hair out in Baal's throne room, which is a separate story...
The issue I have with Spearzon is how you achieve all that. Having to reapply Fury via Takedown every 12 seconds or wasting a number of your hits to maintain it is a pain in the ass and without Fury you're almost useless, it's an essential mechanic. Another thing, it takes 5 hits for full effect. That's a good portion of your potential damage wasted on maintaining buffs. Another buff, Fend, eating half of my mana pool every 30 seconds is not fun either.
I'd like to see the Fury duration be longer or, even better, the number of hits needed for full effect reduced to 3, for example. That would make the Spearzon gameplay smoother and less annoying. I watched a streamer play melee Necro and it was basically the same experience, only Necro doesn't have to constantly rebuff itself and has a better AoE.
Now, the Lister experience...whoever designed that part of Baal's throne room, screw you. It's such a pain in the ass for melee, I have no words to describe. Having to chase after Lister's harem of hags running around the room and nuking you while Lister sets his fields of fuck you all over the place is so annoying...Then, once you finally clear them out, you have to chase after Lister himself who teleports as soon as you get near and still pops his crap relentlessly, with Baal decreping you. Even if you manage to catch him in place for more than 2 secons, he nukes you so you have to run away without barely doing damage. On top of all that, having to build up Fury stacks in order to do anything at all, almost made me punch the monitor...
I know he's not the only teleporting miniboss in the game and they are the bane of melee characters, but those used to be reserved for rifts and ubers, not this early. Lister is a big fuck you to melee and whoever redesigned him doesn't seem to get just how frustrating he can be for a fresh player with a squishy, undergeared and unoptimized melee character...
Another thing I'd like to adress are the stat requirements for gear, namely STR. It always annoyed me how my main focus for gearing while leveling is getting enough attributes, instead of experimenting with gear and finetuning your build. It's so dumb that you won't have enough stats for stuff that you want to wear until you hit 110+ and you're basically pidgeonholled in using multiple pieces of gear with %attributes and/or a big boost to desired attribute, regardless of how beneficial it is to your build, or you're doomed to use low tier/weaker gear until you finally hit 115+ farming spots. It's even more emphasized now, when you should maintain gear progression in order to deal with tougher monsters and harder leveling but you can't because you're gimped by the lack of stats. Again, experienced players might know how to get around that but I have inexperienced ones in mind and fresh/SSF characters with less wealth.
So, having attribute requirements for gear lowered (primarily STR) would be really nice, at least for gear you have access to prior to getting to SUs and farming areas...
Those are thoughts on leveling in 2.0 so far...