Not so impressive if compared to other research results.
According to the mentioned paper the full computational complexity amounts for AES-128 - one of the most used implementation of Rijndael - key recovery is about 2^125. No doubt this represents an improvement over any brute-force but I would not be so impressed.
There are other papers showing different attack techniques and most of them would deserve more attention.
I.e. a theoretical attack on the AES-128 block-cipher was proved two years ago ("A related-key distinguishing attack on the full AES128")
As stated into the paper, the computational cost of this kind of attack should be 2^45. IMHO this is more impressive that a new attack technique "that is (slightly) faster than brute force".