From my experience..
Exploration for quests felt a little underwhelming. It is there, but no more than in any other MMORPG. Most quests will be found by simply following a quest and picking up quests along the path of your active quest. Granted this still leaves one or two left but as with Skyrim those too are easily found through gaps in the map (points of interests are fairly predictably placed on the map, so you will have a good idea is something is missing - as in Skyrim). Most of the 'NPC runs up to you' quests are triggered through reaching certain areas (some towns have an NPC run up to you upon entering) or through progression in certain quests.
Don't get me wrong there is still exploration in the game, though this largely takes the form of gathering to find materials or chests (though this hasn't been improved from other MMOs and many are fixed spawns or a few potential spawn locations per node / chest) which makes chest farming somewhat easy to monopolize in an area. Also there are crafting areas which allow the crafting of sets to be found (though some of these will be en route or near quest areas). Skyshards have hints associated with them so finding them is far from difficult (thus far). The random encounters are a nice touch (seems like a randomly generated mini event at set locations, not quests).
Combat has little feeling of impact. This isn't as pronounced in first person (though far from ideal) but is really bad in third person. Sadly however first person isn't ideal for the tells mobs give with some moves (red markings on ground).
Pacing of quests seems a lot slower than many other MMOs. Whilst the writing in the quests, and imo their execution also, is better than many other such games there is the feeling that they can often seem a little drawn out, as there is less emphasis on combat than normally found in this genre.
Whilst I enjoyed some of the challenges I can guarantee some aspects will prove too difficult for others. The dungeons will not be PUG friendly as I can guarantee there will be people playing with an 'anything can work' outlook, and while it might succeed the pain involved will cause the downfall of many groups. Certain quests also seemed to make people upset in the beta (Gutripper(?) and Doshia being the 2 most common). However most of the content would definatly not be considered challenging (you can still level without spending any skill points or increasing your stats quite comfortably - tested to 13 on one character).