It's hard to give it a proper rating — easy 5/5 for historical impact, but most gamers have no want/use for OG Counter-Strike (especially with no AI opponents, making single-player play impossible). The community keeps the game alive, but exploring the full wealth of mods/maps necessitates leaving the Steam ecosystem and delving into Gamebanana and ModDB, and the like.

All I'll say is, wait for the "Valve Complete Pack" to go on sale for like $10 (less if you already have L4D/Orange Box games) if you'd like to add Counter-Strike and its associated games to your library.