Which slider do you mean? For the Home Page I used Revolution slider, and the Home page simple version is Flex slider. Cheers
In general the theme seems ok, but you need to do more changes.
First of all, the footer can be improved. Try some different social icons. Change the star list style. Modify the color of big box in light grey, and the small box in dark gray or even black (then you have a smooth transition from white(content) to black(end of footer)).
Improve the slider. Not only images. Add html captions.
Add inputs css style. Even on focus, etc.
Create for hover elements, transitions, effects in css.
I think you may change the logo font.
Modify the color of drop down a little bit darker, so can be distinguished from the content.
Finishing elements will help too.
Good luck next time.