Schaumschläger
Froth-beater, also the word for a whisk. Duden defines it as a person who pretends to qualities or abilities that he does not have, especially from a need for recognition.

Blender
Dazzler. Someone who wins people over with outward advantages and so hides his weaknesses.

Phrasendrescher
Phrase-thresher. Someone who makes speeches that sound fine but say nothing.

Wichtigtuer
Someone who makes himself important.

Selbstdarsteller
Self-presenter. Someone whose actions serve to display himself.

Heiße Luft
Hot air. Das ist doch nur heiße Luft. That is only hot air.

Angeber, Großmaul
Show-off, bigmouth.