One of my colleagues practices Yang Tai Chi, but she's recently started learning Chen style - as opposed to me who started with Chen Tai Chi then moved onto Yang. It was funny... she was telling me that she's finding Chen style difficult because she finds it "so different" from Yang, whereas I find Yang trickier because I started with Chen. For those who may not know, Chen style is generally uses more "broader" circular and "explosive" movements, whereas Yang is relatively more linear and their footwork lacks the ferocity of Chen.