webplayer is interesting for small game and puzzle game but not fitted for an fps or an rpg..
i wouldnt say that, a web player could do alot for you in terms of marketing, why make a demo that people dont wanna download when you could just have it load in a web page, much more viewers, have you seen interstellar marines from unity? theyre doing great stuff using the webplayer...
i personally would only use it to get public attention