Some Features of PCFGs
A PCFG gives some idea of the plausibility of different parses. However, the probabilities are based on structural factors and not lexical ones.
PCFG are good for grammar induction.
PCFGs give a probabilistic language model for English.
The predictive power of a PCFG tends to be greater than for an HMM. Though in practice, it is worse.
PCFGs are not good models alone but they can be combined with a tri-gram model.
PCFGs have certain biases which may not be appropriate.