Issue 1: Gimped character creation
Page 66: Adepts have a pool of points equal to their magic (as listed in their Priority table, before any adjustments) that they use to purchase their powers.
Page 156: Whenever adept characters gain a point of Magic, they also gain a power point.
Page 81: Adept Archetype
Adept Powers: Combat Sense 2, Critical Strike 2, Improved Reflexes 2, Killing Hands
(2 x 0.5 + 2 x 1.0 + 2 x 1.0 + 0.5 = 5.5 Power Points, with 6 Magic)
If I begin play with an Adept Priority D, Magic 1, and use adjustment points to raise Magic, I get no power points for the increase, according to P66. There is, then, absolutely no point at all to raising the Magic above Priority Table. There are a few powers that include the Magic rating, but for the P81 build which is common enough, it has no usefulness at all.
And then we have that P81 build, where the design completely breaks the P66 rule. Whatever the Priority, he cannot have more than 4 Power Points to spend. The two adjustment points gave him none. But you have 5.5 spent anyway, which seems an oversight. Unlike Mystic Adepts, Adepts cannot use the 5 karma/PP rule to raise PP.
I can predict the Adept player's argument for full 6 PP, "P156 says I get a Power Point for raising Magic. Am I not raising Magic when I used adjustment points to increase it?" It's a valid perspective, and given that matches previous SR Adept philosophies, I have to go with that myself. It looks like the P81 build was done on the assumption PP = magic after adjustment, so I suspect this was a late editing change and oversight.
Issue 2: Adept versus Mystic Adept
I don't need to quote text here. The Mystic Adept can buy PP up to Magic Rating at 5 karma/PP. An Adept that instead chooses Mystic Adept, spends all magic on PP instead of spells per P66, and thus begins with the same number of PP as the Adept. So far, they are equal.
But the Mystic Adept can buy PP later. By raising Magic to 6 with adjustment points, the Mystic Adept can use 10 karma at creation to buy 2 more PP and get to the full 6. (And buy and cast spells, for that matter, which the Adept cannot do.)
If the Mystic Adept later takes an initiate level, he does need to spend 5 karma for a PP, but that takes 46 karma to raise magic to 7. The Adept, to get seven PP, must spend 101 karma to get to 7 PP from 4. Over the very long haul, the Adept does catch up around Initiate 7 or 8 (when including the 10 karma for 5 and 6). Not many campaigns will last long enough for that.
There were two SR5 balance points that kept the Adept attractive when compared to the Mystic Adept. First, the free PP for Magic increase, which really only affected character creation. That is gone. Second, no spell would raise attributes above racial maximums in SR5, but Adept powers could do so for physical attributes. The spell Increase Attribute in SR6 now does exactly that, but in a superior way to the SR6 Adept version: Improved Physical Attribute is limited to a cap of 1.5 x current stat (ie. a 6 attribute can be boosted to 9 with the power, while a 2 caps at 3); whereas, Increased Attribute will raise by up to 4, regardless of current stat. The enhanced stat advantage is gone, too.
What's left that the Adept does better?