seven-day wonder

Translations
семидневное чудо
The new gadget was just a seven-day wonder; people soon forgot about it.
Новый гаджет был всего лишь семидневным чудом; люди скоро о нем забыли.
Definitions
A seven-day wonder is something or someone that attracts a lot of attention or excitement for a very short period of time, usually about a week, before quickly being forgotten.