In order to answer the question of whether 3.5e is D&D, you first need to determine what makes something D&D, and it will be a different thing for different people.
For some, it is simply a matter of what the legal owner of the D&D brand calls D&D.
For others, it is a matter of iconic game concepts such as the six ability scores, hit points, armor class, races, classes and levels, experience points, saving throws, memorizing or preparing spells, magic missile, fireball, etc.
For others, it is the game experience of creating a character, fighting monsters, overcoming challenges, getting rewarded with experience and treasure, and making that character more powerful.
For others, it is racial level limits, or non-standardized experience tables.