incrediBILL - 11:30 pm on May 4, 2013 (gmt 0)
I've done them in the past but you really need a tangible way to make sure you're getting some ROI from the activity unless you can afford a big branding experience.
The problem is always the same with trade shows which is the shows you can easily afford don't have the kind of traffic you would like and the shows that do, you can't afford :)
Maximize your marketing money if you're going to spend it. If you go, don't do it half-baked, make appointments with local folks you would like to meet and greet, potentially host a suite and pack in a lot of networking in a night. Many of your appointments might fall through for whatever reason which is why the hospitality suite sometimes works well so you can overbook and get all that show up.
If you have anything new to announce those trade shows are always a good time to do that based on my experience and there will always be some press guy snooping around, best to make sure they know you're there in advance and set up a meeting.
With all that said, I haven't done one in about 7 years so check out the current trade show climate before doing it, ask around to some non-competitive attendees if there are any.