all I know is that I have the operation payback challenge coin, but no real memory of those maps. i do wish they'd bring back some of the operation maps... (santorini anyone?)
The game has changed a lot. The original version of CSGO wasn't even made by Valve Software. But every map in the Active pool is either a totally new map, or is an old one that's been re-built from the ground up.
And I have a few skins and a bunch of cases left over from back then. They were worth $0.03 each back then. But the game has grown 500x so demand has increased while the cases actually reduce in supply over time...
Almost a year before CSGO official launch there was a showmatch for it and it looked awful. A bunch of small things were improved by the launch, but it was not good at all (look back at 2012 CS:GO footage and you'll be shocked). Sound was inaccurate and inconsistent, molotovs and smokes were glitchy, wallbangs didn't work in a sane manner ... it was pretty atrocious. That said, 1.6 was basically ancient and Valve (who didn't develop the game) pushed for CS:GO to be used in competitions, so it was used. Over time it was increasingly improved and there was an influx of existing (1.6 & CS:S) pro players towards the end of 2012 and early 2013; and an explosion towards the end of 2013. CS:GO came out in August 2012, but only crossed over the 100k concurrent player mark (which is the all-time CS:Source record) in ~ December 2013.
Skin betting became rampant on CS:GO after the August 2013 Arms Deal update, with sites like CSGOLounge having absolutely huge overall parimutuel pots on basically ever game. This pushed up the popularity of the game - even a small local tournament could have 10k viewers if the game was listed on CSGOLounge [and the bigger matches had millions on the line].
Eventually, years later, CS:GO was improved to the point where it could stand alone without propping up by the skin gambling - and since then it's grown much further; but in reality both CSGO and CS:S had very similar and buggy first few years.