WordNet (r) 3.0 (2006):

spiffy
    adj 1: marked by up-to-dateness in dress and manners; "a dapper
           young man"; "a jaunty red hat" [syn: dapper, dashing,
           jaunty, natty, raffish, rakish, spiffy,
           snappy, spruce]

The Free On-line Dictionary of Computing (19 January 2023):

spiffy

   /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.

   [Jargon File]


The Jargon File (version 4.4.7, 29 Dec 2003):

spiffy
 /spi'fee/, adj.

    1. Said of programs having a pretty, clever, or exceptionally well-designed
    interface. “Have you seen the spiffy X version of empire yet?”

    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. This word was common mainstream
    slang during the 1940s, in a sense close to 1.