As you can read on my blog here on Amiga.org, I was a Mac user before I got my SAM about a year ago. And while I have kept Macs and Windows-boxes at the house and use them for digital video and the like, I am happy with SAM. (and I sometimes watch DVDs on it without any trouble .. well, some don´t work for unknown reasons, but that´s not a performance issue.)
However, I wouldn´t recommend using it as the only machine and you have to be aware that:
1) Deluxe Paint will only run in UAE
2) Not all USB equipment will work
3) You have to use a postscript printer or some other supported thing (rare)
4) Amigas do crash sometimes and software may have unexpected glitches
5) X11/Amicygnix Software is very slooow - so is Google Docs
