Know how to use "fewer" and "less"? Find out.
1853, of uncertain origin, probably related to spiff "well-dressed man." Spiffing "excellent" was very popular in 1870s slang. Uncertain relationship to spiff (n.) "percentage allowed by drapers to their young men when they effect sale of old fashioned or undesirable stock" (1859), or to spiflicate "confound, overcome completely," a cant word from 1749 preserved in American English slang spiflicated "drunk," first recorded 1906 in O.Henry.
/spi'fee/ 1. Said of programs having a pretty, clever, or exceptionally well-designed interface. "Have you seen the spiffy X version of empire yet?" This was common mainstream slang during the 1940s.
2. Said sarcastically of a program that is perceived to have little more than a flashy interface going for it. Which meaning should be drawn depends delicately on tone of voice and context.