It gives a lot of character to the beer and tends to under-attenuate, even if you mash low. That leaves the beer somewhat fruity/yeasty and sweet. If you like a dry porter made with a "clean" yeast, then it's a bad choice for you. If you like a sweeter porter with a lot of esters, then give it a try (you might want to up your bittering hops slightly, possibly your roasted malts, too, to balance the beer). Some people have had bad experiences with Windsor, but not me. In my experience, it's more a matter of what you're trying to achieve in the final beer. Either Windsor is going to give you the results you want or it isn't. If you want a more neutral yeast and a drier beer, use Nottingham. BTW, Windsor is an extremely vigorous and fast fermenter. Good luck!