I've done both the give it away free/pay what you want, and the charge for it ways, and both have been completely different beasts, as the bands were completely different.
My current band, Sirens in the Delta (http://sirensinthedelta.bandcamp.com) have our EP online, and are also selling physical digipak CD's using bandcamps storefront type setup. We chose to charge £4 for digital download and £5 for a CD, as we need to cover our CD costs, but if anyone only wants a digital download, its cheaper for them, but is actually more profitable for us than the CD. I also feel that your music should always have a value, if you don't give it a worth, other people may not. As this band is a far more 'get out and gig' band, we wanted to have physical merch to sell to recoup the costs that we have outlayed with studio time/cds/merch etc. I have found if you do charge, people don't mind paying if they want your music. We have also had it put on iTunes/Spotify/Amazon/Deezer/etc, just to have it as many places available to buy as possible.
With Dresden (http://dresdenmusic.bandcamp.com) my previous band, we were more of a studio band, with our own studio and producer, so we went the free/ pay what you want approach, as we didnt do a lot of gigs and wanted to be able to get our music in as many ears as we could to increase exposure. As well as using bandcamp we allowed the album to be a featured album on a very large private music torrenting site.
This led to approx 20k+ downloads of the album worldwide, which was good exposure and opened other doors and contacts through them hearing our music. We made very little money from people paying 'what they want' but when they did pay anything, it was very nice to see. We didn't make any physical copies so that meant we had no costs to recoup.
I guess the common theme here is that whatever you choose to do, bandcamp is a fantastic tool for artists to get their music online, its really user friendly, and can be really interesting with its stats, eg. I have found reviews of my band that I would have not seen without having bandcamp tell me where people had come from to visit the site.
I once had a photographer friend tell me that he had increased his business tenfold after taking the advice to increase his prices, as people thought cheap meant crap.
I would say charge for it, post a link and I'll buy it.