BikesDirect (BD) is good if you have a decent idea what you're after (geometry, component spec, style of riding).
If not, it is probably better to stay with a local bike shop.

If you are considering the BD route, here's my input:

BD offers great value on decent quality bikes (bang for the buck) and offers a return policy if you don't like the bike, which is a pain compared to a LBS, but at least it is an option.
I have purchased two BD bikes at two price points -$350 and $700, and for the price brackets felt like I got fantastic value for money. The frame quality is very good and the component spec is excellent (1-2 levels above similarly priced bikes). The compromises? Of course. Below $1000 it seems that the common cost savings (i.e. no-name components) is in saddles (below $400), seatposts, stems, bottom brackets and handlebars.)

Once you hit about $800 or so in the BD offerings, the bikes are largely equipped with known components in those areas.
My son's Motobecane 29er came with a no-name handlebar and stem, which were fine functionally. I ended up getting a good quality stem and bars to fine tune the fit, but would have been happy with the stock components for his needs.