I am currently playing Darkfall, and have been since launch (Feb 25th).
It's an alright game. FPS-style archery and magic combat, and over the shoulder melee. The crafting and harvesting systems are mind-numbing click & wait 10-25 seconds, but the items they produce are very nice.
The skill system needs work. A lot of skills make no difference from 0 to 100, like swim and run. Weapon and magic skills, especially magic skills, take a long time to level up but once you do they, again especially magic, are very powerful.
Some graphics and most sounds need work. The audio is just bad. The world looks great and the shadows are some of the best I have seen in any game, but the animations and models need work. It's all really personal preference; Aventurine has said from the beginning that they were focusing on gameplay first.
Cheating is an issue. Aventurine claimed to have server-side detection but clearly they do not as players are speeding, teleporting, and flying under the world, and getting away with it. It is not very common to find a blatant cheater like that, though, but there are other cheats that matter, like seeing players through walls and on the minimap (radar), breathing underwater, no fall damage, and even rumors of a self-clone like cheat that is almost like being invisible without being able to not attack or be attacked.
PvP is fun. PvE solo or in a small group is fun, and PvE in a large group is pretty much box the mob in and swing it to death. It's not really a PvE game; it's a full loot FFA PvP game-- if you are spotted PvEing, and combat can be heard from a good distance, you are going to be attacked for all those PvE loots you've gathered.
The solo player has a hard time because of the common gank-groups. Small and non-allied clans get rolled by zerg clans and zerg-alliances for their cities and hamlets. Zergs often bog the battle down but can be a real spectacle to watch. Small group PvP is fun, but there is always a larger group out there *grin*.
Hm, I think that about covers it. Bring your A-game if you want to enjoy Darkfall-- it's not your average sandbox. Plenty of footage on YouTube.