IMO, It's absolutely critical that photographers go to portfolio reviews of some kind once you get to a level of proficiency because normally you work in a bubble. You do what you do, and you think your own work is great, but you have only a laser beam picture of your work. But how do other people perceive your work? You really need to know how you stack up against other photographers who are either trying to do the same thing as you or are directly your competitors.
With that in mind, this week at World Photography Organization's SF seminars, I had reviews from 5 different photographers, and this is important because you may end up doing a portfolio review with a person who doesn't like your work and that in and of itself isn't necessarily a bad thing as long as you learn from what the person has to tell you. Really be open and listen.
In my case there were four reviewers who responded positively, and one that didn't care for Message In a Bottle project. Of the four that did like my work, I got some very very good constructive criticism about how I can improve my work, or rather what it's lacking (quantity and quality).
As a direct result of things Scott Thode suggested, this morning I am pruning my classical musician photography portfolio back, removing all the filler images and concentrating on the good ones. This has revealed how much more work I have to do because without the filler there are only eleven images.
So do yourself a favor, when you're ready to get a portfolio review, don't get it from just one person. And get a broad range of people to look at your work; go to a curator, got to a designer, a photographer, a publisher, etc. Naturally this is difficult to achieve on your own, but shows like WPO, Palm Springs Photo Festival, Austin Photo Expo or even Paris Photo make it easy because they bring those very experts into one place for you. I know it can be expensive, but its so worth it, just don't buy that lens, use the money for getting better instead.
You will also want to do your research on the reviewers and select the ones that will understand where you're coming from. If you're doing highly conceptual photography work, you don't want to be reviewed by a photographer who only does landscapes, chances are they won't really be able to help you.
And when you get home with all this new info buzzing in your head, do it, make the changes that were recommended, it can't be any worse than what you'er doing right now.