I'm sure this has been done to death already and from 1.6 to source. I recently played GO for the first time from the recommendation of a flatmate. Being a long term source player I have to say I think it's dreadful. It seems by trying to compete with Modern Warfare etc. through adding in graphics a features it has just really diminished that sooo pure and simple game play. The things that bothered me most were how slow the walking is, the extremely stupid spawning locations for deathmatch and the lack of ability to choose your sever. Custom servers are such good fun and a really important component from the original modding scene I think.
To get onto private servers there should be the option to 'Browse Community Servers' under play, you might have to enable it in the options menu (haven't played CS GO in a while). Or you can use the Steam desktop server browser. There are certainly lots of custom servers kicking about, although Valve are keen to direct new players into their ranked walled garden. I agree about preferring Source, but I prefer Source over 1.6 as well, which apparently makes me a scrub.
Blasphemer!  Jesus I haven't played cs in so long. Or dod. I now feel the need for a lan weekend. Throw in some swat 4, raven shield, ts. Ah that sweet smell of nostalgia and the horrid stench of shoddy sound card drivers.
1.6 was much better than source - It peaked around BETA 6 for me, the balance was never quite right again, and everything except the AWP/AK/M4 became pointless to use.
