dreadpirateroberts
A good snapshot of the band at this time, I do have a soft spot for this compilation. Drawing the singles and the occasional album track from the band's first three releases, it's probably a nice place to start for someone new to Santana.
Songs like 'Black Magic Woman' and 'Oye Como Va' will showcase them at their most effective in the early days, while at the same time introducing the signature Santana sound, with its mix of salsa, blues and rock. "Greatest Hits" also features more 'sing along' pop moments like the pleasant 'Everybody's Everything' and 'Evil Ways.'
Some notable absences (especially 'Incident at Neshabur' or 'Toussaint L'Overture' and 'No-One to Depend On' from "III" for instance) are partially made up for by having the surprisingly effective 'Everything's Coming Our Way' and 'Se acabó' which represent two of the better album tracks present. Admittedly, it is called "Greatest Hits" and so you should expect a focus on (charting) singles from their most commercially lucrative period.
A more comprehensive collection, even something like Sony's 'Essential' might be better, or for someone who finds themselves enjoying the music but wanting to hear the band stretch out, simply collect the bulk of Santana's 1970s output, paying special attention to "Caravanserai."