Here is what I've noticed immediately old versus new:
Old - Any combination of class traits was mix and match-able. The only limitations were the amount you could physically slot.
New - Tree system requires you to unlock traits through points spend.
Old - 'Respeccing' was cheap. They couldn't make it free, of course for lore and content purposes, however it was sometimes cheaper than a horse ride to another town.
New - First respec is almost 1 gold at level 80 with 50 points spent/applied.
I am not so adverse to the new system however dislike it for the fact that it :
A) Too closely resembles other games
B) It's progression based. I have to not only unlock augments to skills, I have to unlock the skills themselves(All that coin wasted on skills down the drain btw).
C) Your non specialized tree features cost two to rank up, as opposed to the one for your specialized line. With 50 points to spend, you're looking at 75% completion of one tree, with a handful of points left to spend - which do not go far in other trees when they are two points per rank up.
D) Respecs. They couldn't give us free respecs for say even the first month? Really? And 1 gold ? Come on...
E) Cannot find a keybind for the line swap, have to open menu and mouse click each time.
F) When you switch specialization lines, it does not save all of your hotbutton/hotbar layouts. It simply removes abilities forcing you to have replace them from the skills menu.
G) 'Alternate skill bar' is available for intermediate or reactive abilities that become available after an effect is achieved. These cannot be dragged to hotbars, they do not exist in your skills menu and they cannot be key bound.
If I've missed anything...