I have been a part of a few meetups, and I think that Meetup the application is great when you have an existing community that you want to bring online. If an email list isn't enough (and sometimes it isn't) meetup can be a great way of extending an existing community online. However, if all you're doing is meeting once a month, Meetup is overkill.

It may work OK for generating new community and connections, but as the parent said, you need to have some staying power, and that is either going to be related to some kind of revenue (leads, etc) or some really dedicated hosts that will probably burn out in a few years.