PvE is way harder, just not much smarter. A year ago you could used to just go to Dath and blast away at mobs 50+ levels than you and get like 1 level every 20-30 min. Now the creatures have specials, like root and "punishing blows". Basicly if you fight them to long they're gonna nail you with a heavy dmg hit. Bosses and chevroned mobs can't be soloed so easy like they could. But now there has been an upgrade to terminal mission you can do 10 a day and they give you about 1.3 levels after you do 10. But they just nerfed them it seems you can only take 1 at a time now instead of 2 at a time..
Combat is more complex now, your stats mean more. DoTs are no longer as harsh because now armor also means more, as in the type of armor which each type gives a resist/asorbtion of DoT, the more you stack in that type the better the resist. I put together a bleed proof suit that is virtually bleed proof by stacking armor type, SEAs, and PuPs, all having to do with resist/asorbing bleed (anti-BH suit). The same thing could be done to resist fire or combining different armors for less effect but broader scale of protection.
Now theres powerups (made from junk loot) again and more character mods to powerup. Then theres all the buffs.. Ent buffs, med buffs, officer, GCW, the game has more layers of comlexity now, but after a learning period it is not that hard though at first it sorta is.
you can solo 3-4 non elite blue cons or solo 1 elite not like how we could plow through them a year ago, solo is still possible but leveling will go much faster with 2 ppl plus less monotonous I'd imagine. If you take on too many mobs now you go down like in other games like EQ.