I've only been to a handful of SMART meetings - four different meetings (though one of them I went to several times). Of the four, they followed the same basic format, but of course they were a little bit different depending on the size of the group and the vibe of the people there. I found the meetings helpful, but they were all so far away from me that it was not practical to make them a regular part of my program.
I personally liked the format of the meetings. They were led by a trained volunteer facilitator who presented a topic (one or more of the SMART tools), and then the topic was open for discussion among the group (as opposed to most XA meetings, where you have your one moment to "share" or not). Often the facilitator would ask about problems that people in the group might be experiencing, and he/she would then use the example to show how one of the SMART tools would be used to work through the problem.
I would highly recommend checking out a meeting, even if you're not sure whether you want to quit for good or not. (And these meetings are open to all addictions, including behavioral-type stuff, so it won't necessarily be just alcohol/drug addicts.) I'm not a particularly social person, but I felt comfortable at the meetings I went to, and I certainly felt no pressure to start working the program or to "keep coming back" (or to do anything at all, for that matter).
I hope that helps, and good luck in whatever you choose to do. :-)