I'm not very far in and haven't gotten a companion yet. Here are my impressions thus far.
A) Quests auto-update and change as you go through them
This is a big plus for me. For a long time, in older games, you would have all the objectives as is already on there, and you would finish a quest and get a new one added.
B) Dialogue trees
Even if they don't lead anywhere, the conversations are nice.
C) Voice acting on the main plot
This is becoming more common as MMOs continue. This is nowhere near lets say, SWTOR, but feels more than I remember from WoW.
D) Player created Missions and stories
I suppose people who played City of Heroes might know about player created content. The Forge lets you create a series of events and combats for the player to deal with. I haven't explored it much yet, but I've played one level, and the amount of things that they did, were nice, and I can see a great deal of possibility in this game.
E) Dynamic, action based combat.
I feel that the game's combat is similar to videos I've seen of Wildstar. You see where enemies will attack, and you dodge those areas, while playing an almost 3rd Person Shooter. Very fun.
F) Group Events and Beatdowns, ala Champions Online
These like mini-instances. Go in, fight off waves with a team, and take down a big bad. Your involvement decides your reward.
G) I haven't felt the pressure to buy yet
10 levels in and I haven't felt any restriction to my game play. Not saying it won't happen eventually, but they have a game that is more than fun enough on its own, and they give you space for profession materials, and I've earned one extra bag so far (which I haven't even needed yet).