Not my first Gamejam, but my 3rd, however it's the first time I try to do something in 3D and there is a difficulty spike (for me who have daily work, and don't learn Unity everyday but rather "when I got time"). It's just 1 dimention more but it add a lot of options. With 2D I would not have problems and if I would continue any of my projects, I would definitelly start with my previous 2D games. However it's nice to learn some functions for 3D world. My game won't be much (if I can make it) but I can learn new things and that is important. I create not to compete for the best game, but rather to learn.