1. Is it good?
2. If it needs a source game, does TF2 count?
3. Is it non-complicated enough for my type of guy?
1: Its highly enjoyable, with all the Add-ons and the fact that you have a large inventory of props can make the game last a good while. Planning "Kill Breen" missions, making bases, exploring maps like gm_bigcity, Helicopter Raids, RPing, and like much more.
2: TF2 should work but I recommend getting Gmod bundled with CSS since lots of maps and gamemodes use CSS content.
3: It's not too complicated, but stuff like Wire and E2 need to be self taught over time. Don't worry though, its fun to do the basics and stuff.