Instead of a single window, the new client has three windows (the board, the chat log, the game log) that don't stay locked in place (last I played, at least), and had to be rearranged every time you launched a game. Further, the visual display was more decorative than functional, and I found myself taking ~80% longer to play out my turns. It's was embarrassing for a Beta, and from the complains I'm hearing it hasn't improved.
In the end I simply have no desire to spend my money or time on that client. And jeez, even the free Netrunner OCTGN plugin manages to be visually superior.