We'll start out with the obvious: it's free! Yes, you can pay money for shop items but for the most part, everything you need to reach endgame content is available for free. You can even use in-game currency to buy the REX currency from other players so that you can get the extra stuff not easily gained through the game.
It has some of the same activites as most MMORPG's like crafting, auctionhouses, mounts (ground only), guilds, tons of quests and PVE/PVP. And when I say tons of quests, I mean that you will still be doing quests at max level, including daily crafting quests if you want. They're the usual run of quest styles like: make so many of this item, kill X critters, close rifts, take ITEM to soandso or talk to this person. My favorite is talk to someone standing right beside a quest giver, like they aren't on speaking terms.
The major difference is that in addition to having two conflicting sides that contend for control, there's also lots of rifts that spew out various elemental mobs to kill for Planarite. This currency is used to buy uncommon, rare, and epic goods. There's a lot of helpful people on the chat channels plus tons of guides for the 4 primary classes and all the possible subclasses. Rift also has a form of player housing that they call dimensions; you can get items to place in your dimension from crafting, looting corpses, daily freebies from the Rift Shop or as quest rewards.
I can only think of one so-so item worth mentioning and that is collectibles. There are several "artifact" sets that players can collect for various rewards. Collectibles can be either good or bad depending on your point of view. It can be frustrating trying to get everything since these artifacts can be hidden anywhere in the game world, as daily rewards from the Rift Store or as loot. Each zone also has fishing artifacts called trophy fish that can be used in multiple collections but you have to have one trophy per set, which means lots of grinding.
Right now a couple of the bad aspects are lag and a smaller playerbase. Rift is about to release the 3.0 Nightmare Tide expansion on or around Oct 22nd, so that should bring more players back to the game. Most online games have lag so that's not surprising. One other negative thing is there's no real flying so players either walk, ride mounts or take the portals to get places.
Anyone else have something to add to this short novella?