It looks great, no doubt about that. What are the advantages compared to GCCG?
1. No installation required.
2. Works on all platforms.
3. Faster gameplay, as you don't have to manually add twilight, wounds, etc.
4. No cheating possible, therefore fair competition, so leagues and tournaments are a possibility.
5. Extensibility, hence I can build extra features on top of the platform, like sealed leagues, where you are allowed to build a deck and play only with cards you have in that league for the duration of the league, etc.