  A recent paper [Burovski et al., cond-mat/0507352] reports on a new,
high-accuracy simulation of the classical phi^4 model (in the three-dimensional
XY universality class). The authors claim that a careful scaling analysis of
their data gives nu = 0.6711(1) for the thermal critical exponent. If correct,
this would neatly resolve the discrepancy between numerical simulations and
experiments on 4He. There is reason, however, to doubt the accuracy of the
result. A re-analysis of the data yields a significantly higher value of nu,
one that is consistent with other Monte Carlo studies.
