Hows the leveling process? Hows the end game?
Leveling process is easy and is essentially what you want to make of it.
If you want to level in PvP, you can. (Slowly.)
If you want to level off of quests, you can.
If you want to level off of chasing rifts and shutting them down, you can.
If you want to level off of pure grinding (instances), you can.
If you want to level off of just exploration, you can to a certain degree (because you will run out of places to explore).
If you want to level off of tradeskills, you actually can (very slowly) by doing work orders. As long as you can get the materials for them...
Leveling is very forgiving and can handle pretty much every spec under the sun (other than not putting any points in anything). Instances are less forgiving since people usually don't want to do them over and over unless it is to faction farm.
Endgame is Expert Dungeons, Expert Rifts, Raiding and Raid Rifts for the most part. They are including instanced 10-mans in the next patch as well. Each side (Guardian vs. Defiant) also has an over-arching Epic quest line that you will want to do. This quest line starts at ~level 18-20 with stuff to do every 5-10 levels or so. The quest line itself goes through a ton of things and pretty much showcases what you would be doing in endgame by giving you some goals to accomplish to progress the quest line. You can, of course, ignore it, but you *will* miss out on things if you do.