Good overall composition, the eye is nicely led across the painting.

Your biggest problem is one of being consistent in your painting.
The tree trunks suddenly get very thin from thick, and you over did the above ground roots a bit too much.
Your coloring is also inconsistent. This is most noticeable in the sky. Generally, the sky is slighly darker at the top, getting a little lighter as you get nearer the earth. Your sky has like a "light colored halo" around the picture.
This brings up the biggest consistency problem, the water reflection. Your sky is darker and bluer, with clouds that the sky doesn't show, while your trees are LIGHTER in the water reflection. .

You also have the edges of the water a bit too perfect, more like a swimming pool or a puddle after a rain. If you study some photos of landscapes, you will see that nature is seldom quite so regularly shaped and spaced.

Here is an example to show you - Notice the coloring of the sky and the trees, and along the edges of the water:
http://www.sxc.hu/photo/1076964

It's a good start, you will get better the more you practice.

cool work...gl

For someone that is new to painting you surely take on a difficult subject matter in a bold fashion. For this you are to be commended highly. Honestly I can not say enough about the courage a person displays when trying something new and then posting it in a forum such as this. Way to go Man!
As far as suggestions for you to improve.........do another one!
Message me if I can help at all. If you do Netflix there is an Acrylic painting video under special interests. Follow along and they will have you moving ahead fast. Best of luck!
Oh.....and fan brushes are great for grass.

Yes...I agree with above....keep painting and paint what you love!!!!! Good Job author!

Thanks all for your comments, specially the tips and suggestions.

YOU are so brave.
like i said on another comment, i tried...i tried with a valiant effort, and wasnt' happy with any of my results in this one...so i give you high commendations on givin it your all.
honestly, a landscape is one thing i didn't think to be so difficult til i set out doing it..and i realized, i really had no idea what to do with it. ..
Good luck on this, and all your future ones. i look forward to seeing you grow as an artist!!!