The international lock started off his career with Gloucester and is is back in Scotland for the first time as a professional.
Speaking to STV Sport, Craig said: "It's been great, it has been a good move for me in regards to being closer to home.
"To join a team like Glasgow, especially with the success they have had in the last couple of years, the players have really bought into what Franco is doing here. It's been really impressive to see.
"To be part of it now is exciting for me. I have played in England and Wales now, seen different ways of playing the game and played with different players, so that has been good for my career and my development.
"But it is exciting for me to come back here, with everything that is going on in Glasgow, and you want to be part of that.
"The team is just trying to go from success to success, so it is exciting.
"The team has set high standards across the board, so silverware is 100% what we are going after this season.
"Every game is a new challenge, and we are always building towards something."