I played it for years; met some good friends there, got into the circles of some professional players and made some interesting videos. I first played an early beta, then came back to it at 0.6 and 0.65. I don't see why many people dislike CS:S, because the 'Source Engine' improves the experience.
Those who "hate" source are free to have their opinion, yet I don't see why keeping an old and fairly bad--1.6 was pathetic in my opinion; if you want 'old school' then go back to before version 1.0 and play it with bunny-hopping and all of the current weapons--version of a game that's now been greatly improved in terms of graphics, gameplay, physics and networking (IMO, though I'm sure some would disagree) around is all that fun: things have moved on and 'CounterStrike' has improved...
I think that certain people take it too seriously; it's just a game and the chances of becoming a professional player are extremely low... I've met so many people who've told me that it was their goal in life, after having thrown away their education and even their jobs.
I wonder if any of them actually managed it... But I doubt it as the competition is very fierce.
Most popular multi-player game of all time, certainly. A great title and not one to be missed. Might add more later...