When Should I Explore The Jungle?
I usually immediately farm eaters, get a full set of Shadow Armor, hit up some sky islands, and then head to the jungle (before the dungeon). The Ivy Whip is way too useful to ignore for long, and the Chakram is nice. The blade of grass is solid (great reach, but the lack of knockback can be a problem). As of right now I think the jungle has additional items that are intriguing. The Boomstick (jungle shrine) is an excellent gun; it fires 3 projectiles (in a randomized spread patter) for the cost of 1 ammo. It makes quick work of the Eye of Cthulhu I found, and I am eager to try it on the Wall of Flesh with meteor ammo. It's a great normal mode weapon. You might be interested in what the bee hive has to alter as well. Honey can make some great healing potions, and some of the Queen Bee drops are interesting, but I'm still looking at how I might incorporate her drops into my strategy.
A Demon Bow suits my jungle monster killing needs just fine, even with wooden arrows. In fact, it's the second demonite ore item I make after the Pickaxe. I switched to the Boomstick when I found it. The Jungle used to be great for topping off your hearts, but I found them more plentiful in normal mode this time and so this benefit was reduced (the same is true of the dungeon, both before and after 1.2).