Anyone used Mono on Mac before

A few days ago, one of my client wanted to port a small dotnet app (that I made from him) to Mac OS X (Lion).

I've NEVER used a real Mac in my life.
From DOS 6.22 to Win8 DP - I am a life long PC user.(and Unix/Linux)

I have no desire to learn any new programming language to program in Mac.

So, I was thinking, instead of rejecting the work, I'll use Mono on MacOS X to convert the code. The client agreed that he will give me remote access on the Mac.

Anyone used Mono on Mac before ? Is it good for building 'professional' Mac apps ?

If you have used it before, I'll be glad if you can share a few tips & traps that you've found.

Thanks.
:)

Was the app written for framework 2.0?

The last thing I heard about Mono was that it was 2.0 compliant, but nothing more recent.

It is compiled in 3.5, but can be changed to 2.0 without any change.