Warlocks and their new stupid "Curse Stance" powers that require multiple new keywords.
The fact that every book comes with a new Warlock pact. I half expected Martial Power to have a warlock pact in it.
Summons which work different than the summons from PHB2 (i.e the wizard summons).
Dynamic Tags that escalate into other dynamic tags (Wyrm Form and Cloud of Flies)
WOTC's desire to create a seemingly endless array of Paragon paths.
Dancing Bolt because it grants the same action twice....once on a secondary target and once on a primary target.
And of course....
The lack of PDFs :(