Long-time readers know I believe the answer is "of course."  Seth Godin lays out both sides of the argument is a recent post and urges people to choose one approach or the other.  Actually, you choose to invite criticism or you automatically default to the option of not doing so.  While the reasons for not inviting criticism might be of interest in a high-turnover business, it is difficult to imagine a cogent argument for not keeping clients happy (including finding out what you can do to improve) in the legal business.