Support is low - though it took a while to build the initial technology. I get a lot of traction from realtors and lawyers. I've tried paid advertising but the conversions are too low to make it worth it.
Initial goal was "vacation money", and it's currently on track to hit that level next year.
I've had a similar service, http://dbinbox.com/, slowly growing with entirely free plans for the last ~year and a half up to ~25k users and am about to add premium plans.
The site is a bit lacking in documentation (typical side project issue). It's $3/m or $30/year. I get a good mix of both types of subscriptions. I figure the price is low enough that it's not a barrier to entry for the majority of people. I also need to document better what premium accounts get you (ability to upload to different folders, etc).
I experimented with adwords and stumbleupon but nothing caused enough conversions to be worth it. Every now and then I turn adwords back on to play with keywords a bit, but it's just not worth it at the low price point.
No it isn't :)