  Monte Carlo (MC) simulations have been performed for a refined estimation of
the correction-to-scaling exponent omega in the 2D phi^4 model. The best
estimate omega=1.546(30) has been obtained from the finite-size scaling of the
susceptibility data in the range of linear lattice sizes L from 128 to 2048 at
the critical value of the Binder cumulant, this result is confirmed also by
several other MC estimations. It served as a basis for a critical
reconsideration of some earlier theoretical conjectures and scaling
assumptions. In particular, we have corrected and refined our previous analysis
by grouping Feynman diagrams. The renewed analysis gives omega = 4-d-2 eta as
some approximation for spatial dimensions d<4, or omega approximately 1.5 in
two dimensions. Our MC value is comparable with the known results of the
epsilon-expansion.
