Wish people would hold the fish up near their body instead of out at the camera if they want folks to guess the weight. The only reference point then becomes your hand, not your height.
Example, this picture is of a 4.5lb bass. I weighed it myself.
I already gave Jim a ribbing about holding the fish out, so I don't think he'll mind the example. It makes a good picture because the fish looks huge, but it doesn't help much for accuracy.
This fish is the same weight as the one above but doesn't look as big.
^ This one weighed 6 and 1/2 lb. Again, weighed it myself using the same scale as the others. It's just really hard to guage it very well from a picture sometimes.
It's a nice fish, can't say about weight without better frame of reference or length. Best guess would be 4 to 5lb class?
What Surfrider said. Beyond saying its a nice fish (which it is), its difficult to estimate especially when you are holding the fish out. People there (including yourself) have a much better opportunity to estimate it. That fish could be 4 pounds or 6. I keep a ruler stuck on the thwart of my canoe ( for legal flounder/red measurements). Using published length to weight estimates gives you a better idea. But its really not important. Its a nice fish.
I second what Sam said. The Bass Master pose makes for a good picture but makes judging size near impossible. With the proper pose you can make a 3 look like a 6. I personally use 3 poses depending on if I'm taking a selfie or someone is there to take the pic for me. It may be a bit boring but I can always compare size.
My best guess is your fish is in the 4-6 lb range. Photo debate aside it is a nice bass.