I have used it a bit on a reasonably high traffic site (but if you do this, be careful - make sure its a site where people don't mind) and honestly, it wasn't really worthwhile. The payouts are much too small. I may be wrong, but Bitcoinplus seems to share equally between all miners, rather than proportional to the CPU power put in. At least, a similar number of mhash/s in a normal pool gave me much higher payouts.