There are sites with bad graphics and clunky UI, but there are definitely some with good graphics that don't make the eyes bleed and butter-smooth UI, so that isn't as big a problem.
As others have said, relatively low traffic is the biggest problem right now.
Freerolls have their place in letting new players try out the site risk free, but as far as growing traffic, I think competitive bonuses/promos, lower rake/higher rakeback, worthwhile vip programs, guaranteed tourneys and good graphics/UI are better for attracting action players who generate rake and help grow the site.
Graphics is something I can live with, but the thing that irritates me the most is the speed.
Some poker sites take hours to load. By the second click, i am gone.