/What I did not like about my Giant was the sizing. Not specific enough. They will try to convince you that 3-4 sizes are all you need cuz you can adjust the fork, and seat, and blahblah, but all that translates to is taking your cash.
Roadies are going to tell you go with a road bike cuz of speed; mtn bikers are gonna tell you to go with theirs cuz of the shocks and suspensions, etc. What it all boils down to is the type of riding you end up loving in the end, so definitely start out cheap cuz if you end up loving to ride, like I did, your 2nd bike will cost a grand or better.
A good starter for both tar and path is something along the lines of
this. Of course, Huffy's and the like from Walmart or even Sports Authority are a good start too. Remember that you probably will not stick with your first bike for long, either because you don't like riding, or because you like it too much and want a really good bike. So don't spend alot the first time out.
Trust me on this one. I learned the hard way and spent wayyyy more $$ than I needed to by not following this advise.