Not entirely sure I agree with what you are saying here. On first read it feels more like the feed back you'd expect from someone who is used to playing MMORPGs, where you can't go more than 10 minutes without getting another level or another piece of gear and the "challenge" is getting to the endgame to play with your mates as fast as possible.
1) If it's the sword from the prologue then I'm not surprised you've not found an upgrade for a long time. It's a very powerful sword for that point in the game, but the first act isn't scaled around you having that item, I skipped it on my Ranger and Cleric and both replaced their main weapon a couple of times in the first act, not to mention several other pieces of gear. The power growth in this game is slow and that isn't a bad thing, there's a ton of optional things to do - things that arent the "main" quest) and then you have the option of rapidly increasing enemy power levels throughout the first act - forcing players to do those optional things, or save scum harder to get the outcomes you need to maximise your XP and gear intake - or making certain aspects of the first act "trivial" for players that did them later than the developers planned. The way it is now, if you choose to do the area to the south first then east then north it's just as challenging to you as someone who started at the north and went round that way.
2) Yeah some classes can be a bit short on choices at certain levels, but I'm pretty sure there isn't a class where you don't get something each level (even if you can't choose it). But the slowness of levels comes back to my point above, the optional order means keeping the right level of challenge for players at all times. I like planning out my characters in detail in computer RPGs, and I'm not finding that this game prevents me from doing that.
3) That fight is a step up in difficulty that is for sure, it's probably the first big fight where there isn't an environmental "trick" to beating it. Took me a few attempts to beat it on the normal (middle) difficulty but I did without having to make it easier, it' does lean much more into the toolkit you bring (that certain Legendary Item you undoubtedly picked up on your way to that fight is really useful in this fight, plus is selecting the right kind of damage and using some good old Crowd Control and positioning). I do agree that its initial challenge is a bit of a leap over what you've had before, but it's certainly not "impossible" at level 6.
There is an encounter in the last act that is way more problematic that this and feels that you need a very specific set of consumables/spells to realistically beat it (the "cheese" tactic), which isn't great game design in all honesty. But that's one fight out of hundreds and in the act that's had the least early access play-testing.
Not sure why you find the map unreadable or the quest markers unclear (they seemed pretty clear to me as to where I needed to go)
