And most of all- you rely on them to collect your customers' money.
I can say- without reservation, that I made the right choice in going with FastSpring (http://www.fastspring.com):
- Great customer Service- respond to emails very quickly
- Good presence in ISV community- e.g. on Joel on Software Business of Software forum
- No upfront/ongoing charges
- Higher transaction charges than other payment processors
- Easy to customise payment process- e.g. I send a HTTP notification to my webserver to generate a license key
A couple of weeks in however I noticed I was getting hit with VAT on all my transactions. There's nothing FastSpring can do about this- they resell your software, and as a large company are obliged to charge VAT at 15% to their European customers. This is especially painful as all my customers are in the UK- so it applies to every single transaction.
In the hope of increasing my profits by 15% I decided to investigate PayPal:
- More difficult to set up- documentation spread all over the place, and forum answers sometimes misleading
- Low transaction charges
- No support for discount codes/vouchers (this really surprised me)
- No experience with customer service yet- but I've heard bad things
I now run both side by side- though I try to steer users onto the PayPal payment option rather than FastSpring (Buy Page) as I make over 15% more per PayPal order.
Despite this- I still find that roughly half of my users prefer to use the FastSpring payment option- and I'm not really sure why- I'd be interested if people have any ideas about this.