Ask HN: Worth filing provisional patent for micro-ISV product?

Hello HNers,

I'm going to (hopefully) be releasing my first commercial software product fairly soon. The lawyers I've talked to have recommended that I file a provisional patent for the software before it becomes publicly available. This is my first foray into the business world, so I don't know what's typical here.

I come from an academic background, and I can say that there's nothing publication worthy about this software, which makes me doubt its patentability. It's also quite expensive to get a lawyer to do the filing. Can anyone share some wisdom or experience with this?

Perhaps relevant details: I am in the US, working alone, with no outside investors.