I am on my 1.5 playthrough (as I stopped my first one at cca 1/2 of the game and now I am hurrying to the point where I stopped to proceed and then get to the already bought DLCs). UI has been almost totaly disabled (health and mana contextual, not quest updates etc.), but on several occasions I had to temporarily enable the quest markers, as I actually failed to find some NPCs (in Hound Pits, mostly) and running around for more than 10 minutes without ANY clue was not worth it. Blink I use all the time, but the only other skills upgraded and used were/are Agility and Endurance. From weapons, just sleep darts, nothing else, and on Very Hard difficulty. Lots of fun I have with this setup:-) I am not looking for all the coins, all the runes, Ghost stat etc., as I simply do not have time for this, but I keep reading documents, taking side quests, going on Low Chaos and without killing anyone.