Zzzzz....let me know when this gets interesting. Why is it so damn hard to make an mmo that has tons of quests that are challenging and feel rewarding and a nice open world to get lost in?
Uhh... this game has that. It also has tons of simple quests too, but you can skip those for the hard ones. Also, ALL the dungeons are hard. Even taking in high level characters doesn't help too much as the game evens you out. Even doing rifts is like that. Sure being level 35 when taking on level 8 elites from a rift is easier for me than say a level 8 but.... I can still die and have plenty of times. The monsters do more damage if they are +3 levels above you, but don't do any less just because they are lower. The only reason I do better higher level is because I just have more hitpoints and a tiny bit more damage mitigation with a little extra damage. That's about it. Which is why low level monsters do not have any smaller of an agro radius than high level ones.
The zones themselves are fairly small, but everything is specifically placed. This is something I like. For example, most people don't know about the world drops.
Basically every zone gives you an incentive for exploring. The first exploring reward you can find are artifacts that are all over the place. Making an artifact collection allows you to turn in that collection in Merridan to an NPC for an item reward and usually a currency called a Lucky Coin. Lucky Coins can then purchase items off that NPC such as epic mounts. Collecting all the artifact collections in a zone gives you a big reward and an achievement + title at the very least.
On top of that, there are literally world drops and puzzles to do in every zone.
* SPOILER ALERT SPOILER ALERT *
Stop reading from here on if you are the type of person that likes to find and figure things out on your own. Still, I'm not going to spoil everything but I'll give examples of what can be found and done in Rifts.
First off, being on the defiant side, I know their zones and not the guardian zones. So while I explored the guardian zones a little, I didn't take as much time doing so as I will next beta.
So in the starting defiant zone of Freemarch, there is a big lake called the Lake of Solace located in the south of the zone. In this lake there are all sorts of treasures chests, bodies, and what not that can be looted. The first time you loot one of these chests you will get an item called a Wet Sack which is a yellow colored item. On subsequent looting attempts you only get a Moldy Sack which is a grey item.
The Wet Sack when opened has high chance of dropping a blue item for your class in relation to your level in multiples of 5. Meaning if you are level 12 you will get a level 10 item. If you are level 14 you get a level 15 item. There is a good chance of getting a purple instead of a blue item and sometimes you are unlucky and get a green. 6 times out of 10 with a bunch of guild mates looting these sacks we got blue drops. There are as far as I know 6 places to get these world drops in the Lake of Solace plus one puzzle attempt for the zone.
Now about that puzzle, I'll spoil this one for you where it is. Pretty much dead center of the Lake. The puzzle basically is a glowing blue light that travels in a circle. When you click on it, the light stops there but another one continues on. You basically have to click it so that the circle of light is complete. You'll understand what I mean when you do the puzzle as it is not hard to figure this one out. You have a very limited time to complete the circle of light by clicking on the moving light to make it stop. Once the circle is complete you get a key for a chest that spawns near by. You also earn an achievement for doing the puzzle.
Now to let people know, I know of about 3 more + a puzzle in stone fields, 2 more + puzzle in scarlet gorge, 3 in gloam woods, 2 in scarwood, and 1 in highlands. I don't know where everything is at. I do know how to do all three puzzles I have found though and they are all different puzzles. On top of that there are various achievements to accomplish in every zone. Some even have great rewards like hunting of rare monsters in scarwoods. I have not done every achievement for all the zones yet, but it is rumored that for doing so you get a special reward as well per zone.
* SPOILER END *