Hadn't really considered them.

With a quick look at some reviews and features lists of them this morning, it seems as a software category they implement a lot of possibilities for doing things most of us want--accounting plus a lot more. And it looks like several have a lot of support, usually from a company or consortium that charges a monthly fee not much different from the cost of small business accounting like Xero or QB Online.

I'm a little leary of a open source projects in general though. Some of them end up with something stellar, like the Thunderbird email client, which I use. But many of them are incomplete (or maybe at least not complete for things I want!) and no one is directly responsible for adding features or fixing bugs. 

That whole software category also appears to be the same kind of "zoo" of companies and services as the small business cloud accounting world. There are a lot of competing products and players, and none of us has enough time to give one or two of them a deep evaluation to find out whether they will really do what we want...or whether they have some "gotchas"/feature holes that will make them come up short of meeting our needs.

But having said all this, I realize evaluating open source ERP products really is not a lot different from evaluating commercial small business accounting products. Online reviews are mostly worthless, as most of them (like the "Ten best small business cloud accounting products" types of reviews) are simply a hurried listing of features claimed by each product in the review, not a serious evaluation of whether claimed features do what most people want or are easy to use.. Mobile apps are a good example. If you look at the details, you'll find many mobile apps for cloud accounting products are less than great--some have a reputation for being glitchy, and most don't support full functionality of their parent browser-based cloud accounting product.

Have you given a serious/deep look at any specific ERP product?  What opinions have you formed?