I haven't been to a portfolio review since college, so if someone else has a different experience, absolutely defer to them. xD
But if you hope to someday be hired in the industry and publish work with a company, going to a portfolio review is NEVER a waste of time. It's very unlikely that you'd be hired on the spot first time, but you'll get very valuable information from a review of what reviewers respond well to, what they're looking for, and what they're not interested in. If it's uneventful this time, you'll still be much more prepared for the next time.
In general, your portfolio should be only work you're proud of -- (I've heard SO MANY comics editors talk about artists who come in for review, and as the editor starts looking at pages the artist nervously says "well, those ones aren't really my best work," to which the editor wonders "then why are you showing them to me?"), and it should be mostly the kind of work you want to do. If you want to do comics, don't only bring non-comics illustrations; bring in some comic pages.
Most of the actual hiring I've seen come out of portfolio reviews is a company saying "we really like your work, would you be interested in working on [Project] for us?" I don't think they're looking for stories to publish at these kinds of things (companies that are looking for unsolicited submissions will have a process for that on their websites); they're looking for artists they could work with.
I've seen one artist who immediately got an illustration job from a reviewer who loved her work, I've seen an artist who was told she'd be a great fit for an upcoming project and just gave them her contact info so that they could get in touch if and when that project came together, and I knew one artist who constantly brought her work to editors to get feedback at every chance she got, and eventually had a good enough relationship with some editors that they expressed interest in hearing a comic pitch from her.
Anyway, this is my impression from the few times I've talked to editors and the portfolio reviews my artist friends have talked about with me!