We've just taken the POD plunge too, so I thought I'd give you my thoughts following the first few weeks of the process.
Firstly, the quality of the books you get is great. They're almost as good a properly published products. The only thing I can think to complain about (and it's a very minor one at that) is that the cover is a bit thin. But that said, the quality of the production is brilliant. I personally went for slightly higher quality paper for the interior, and it's very good quality.
Secondly, sales on RPGMall are really slow. Our products now seem to fly out of RPG at the rate of 70-80 in the first month. We've so far only sold one copy on RPGMall and even so managed to hit 18th in the charts! Maybe ours isn't up to scratch with some of the other products available, but it serves as a word of warning to any possible newcomers to the POD service. Don't let it put you off entirely, but make sure you don't get too optimistic with your print run.
However, I am hopeful that RPGMall will pick up. I think James is doing an awful lot of work to promote it at the moment, so hopefully it will become much more popular in the future. I'm also hopeful that retailers will learn about it and start to buy from it too. That's when it will really kick off in popularity. We at Malladin's Gate are going to be doing our bit on this score too. My business partner and fellow writer/designer, Nigel, is aquainted with the owner of the Travelling Man chain of RPG stores (largest RPG retailer in the UK), and we're hoping to be able to convince him of teh merits of RPGMall, so fingers crossed...
cheerio for now,
Ben, Malladin's Gate