Hey Obi,
Welcome to Bike Forums! Don't be alarmed at the amount of seemingly hostile responses to threads around here, people are just having a little fun. The bike you posted doesn't look all that bad for $600 new, but I would definitely recommend trying a bike out in person to see if it fits you. The most important (arguably) fit is the reach from the seat to the bars. If it's too long you'll end up with back and shoulder issues, too short and similar. Also, bikes from BikesDirect have to be assembled.

I don't have too much experience with 6 feet people, but you are looking at a larger size than the top of the bell curve, maybe a 58cm? Also never know if your body is going to fit the general description. Some people have really long torsos.

I recommend going down to the local bike shop (LBS) and seeing what you like. You can either buy there or try to find something used on Craigslist. Be sure to have a friend who knows what they're doing inspect it for you, or bring it to a shop before buying to have them check it out.

Be sure to search the forums (by entering site:bikeforums.net .... into google search where the ... is replaced by your search terms. You can find info on fitting, and more importantly: riding posture. During your test rides make sure you aren't locking your elbows.