tangor - 8:04 pm on Apr 11, 2010 (gmt 0)
Entering a saturated niche is difficult, not impossible. Ultimately a good back link profile will do wonders... it is obtaining them that is the difficult part. Offer a clean, good content site, get a few back links, and go from there.
Eventually one reaches a point of diminishing returns (ie. work expended for traffic/rank received). Most of the time that point becomes obvious and at that time one should move on to other things.