Here is my Tamiya JSU-152.It really was a great kit to work on and I am happy with my build.I used Tamiya +Vallejo paint,and weathered with Mig Products.Especially like the Track Brown Pigment + Rainmarks wash.I added Friul Tracks as they really enhance Soviet Armor.The pics aren't great but here goes,thanks for looking.

I like it. The weathering would look better in a dio setting. It seems overdone against that background. Dirt needs to be added to the tracks to match the rest of the body.

I second exer's comments, this beast is just begging for a dio! A agree with your assessment of the kit as well, I'm working on one right now and it's a pure joy to build I'll be using the kit supplied link as they are quite nice in there own right, but the friuls aren't a bad call by any means, they look sweet!

I think using the rain-mark wash, has buried the rest of the build and paintwork. Maybe it looks better in reality, but with heavy weathering like this and just one colour, it leaves the model quite flat in both detail and life. It is quite possible that the photographs give this impression ... light/dusty finishes usually do over-expose in photos. Taking time and making good photos is important, as thats all we see. As already recommended, a background is important.
I also think you could work the fruil tracks a bit more. As they can be kept seperate, you could show a polishing where the metal wheels are running over them ... metal on metal would not have the same rusty effect. The teeth and wheel rims would also be polished. I can see you have metalised the upper details on the tracks, but this has been "buried" by the over-exposed dusty effect.
There are many discussions about weathering techniques today ... what is natural and what is false. Your model has all the natural elements ... dust on top of a flat paint job. I really believe that this doesn´t work 100% on models as a 1/35 model cannot throw shadows like the 1/1 model can, therefore when weathering is added like this, the details dissapear. If you look closer at those models that make magazines, you can see they use the weathering to accentuate the details ... not add a blankett cover, which gives this flat effect.
As the other posters have said, it may need to be placed on a diorama to give it life. I agree ... definately needs something to contrast against the flat colours. Some stowage may help. I think there should also be another figure in the front with the machine gun. Having this hatch open throws the composition of the model a bit.
This is honest feedback from my opinion only. Take it for what its worth ... not very much. You´ve enjoyed your build, so thats why its worth it to take an extra 5 minutes and get the best images you can, with a background so we see the best of your model as well.

Anthony, That beast is screaming to be put in a dio I can see what Frank means about the photos and the flash may try a different back round. I think the brown of the peg board may be mixing to much with the weathering