Alright so I'm not trying to be a jerk or anything, this is purely me just being critical.
What you're going for here is called a
flat design. A minimalist approach to general design.
That's all and well, but I believe the following this can be improved.
- Place a border or something around the image. Most pictures/images are (usually) vectors or images with solid colors (no real gradients). The real image inside the design can semi-break it (unless it spans the entire page then by all means go for it).
- In Photoshop, everything looks fine, it looks simple. Heck it's really easy. What matters is how you break it down, how you code it, and how you put it all together.
To be perfectly honest, I feel like that design is too simple. Colors, while are pretty passive (sometimes not a bad thing), don't really add on to the design as much because there's nothing else. I mean passive colors work very well if it was complementing something else (like another part of the design) but working off of plain passive colors for me is kind of a turn-off. Maybe have the grey darker and the text darker, have the green brighter.
Also, make sure the font is web-ready. It'll look pretty bad if navigation and all that remained as images (especially for incredibly simple things like that).