Synonyms for Smashing (same or very similar meaning)
WordNet sense 1 (very good):
bully, dandy, great, groovy, keen, neat, nifty, peachy, swell, corking, cracking, slap-up, bang-up, not badWordNet sense 2 (having desirable or positive qualities especially those suitable for a thing specified):
goodWordNet sense 3 (the act of breaking something into small pieces):
shatteringFrom the ODE community, based on WordNetadd/edit