Mono didn't work for me. I think it might be okay if you targeted it specifically as your official runtime. But it is not, and I don't think ever will be a drop-in replacement for the MS stuff. I summed up my thoughts here: https://news.ycombinator.com/item?id=2777025

I'm in agreement with wes-exp, even though I still have to make the "long walk home", mono currently offers a workaround or perhaps a false reassurance that when the requirement comes up, you can still run your apps on Linux. Truth is it's lagging behind, it does not enjoy good community support (everybody in the *nix community is against it) and to top it Novell was acquired recently and the new management put a lid on mono. Miguel has started a new company but it seems their priority is standing on their feet first ( making money and being profitable). So, no. Mono is not a good alternative for .net at this point.