Scott Aaronson has commented negatively on a previous paper by the same authors [1]. I don't know if similar issues apply to this one:

[...] the paper advances the prediction that quantum computation will never be possible with more than 3 or 4 qubits. [...] I wonder: before uploading their paper, did the authors check whether their prediction was, y’know, already falsified? How do they reconcile their proposal with (for example) the 8-qubit entanglement observed by Haffner et al. with trapped ions [...]

(Note: that's a critique of the previous paper, not the linked one. Although the linked post mentions quantum computers not working, the linked paper does not touch the subjet.)

1: http://www.scottaaronson.com/blog/?p=1255