My 2¢
1. OK, but nothing out of the ordinary. May work with some cropping if you really need a flower photo.
2. I really like the feel of this, B&W works well, the lighting is nice and has brought out a good tonal range to work with. This is the sort of photo I'd spend a while experimenting with crops, toning, effects etc.
3. Again B&W works for me, but the lighting isn't as kind to the subject and the tonal range isn't as useful. Would be worth another try at this subject with different angles / time of day etc though?
4. Nice idea, I think it needs more heat haze and personally I'd move to the left slightly to miss out the parked cars.
5. Like the concept, as others have said it needs experimenting with composition and maybe selective focus.
6. I like the lighting, the concept and the mood of this, but as others have said it needs much more depth of field.