I've made a couple of changes, mostly adding a second pair of legs.
above pictured with the initial space skulls spider mecha (which only had six limbs and therefore was actually an insect not a spider)
pictured with "goat" walker
pictured with mini walkers
Pictured with various space skulls mecha, demon ogre mecha pictured at rear.
While this is a fairly "functional" Spider Mech, it lacks several attributes of true spiders. For one thing there is no thorax. So my plan is to place a large weapons array at the rear to serve that function.
I like how the legs turned out, but the feet bug me slightly (no pun intended) I'd like to change them somehow but I'm still brainstorming options.
The cockpit is a little bit of an issue for me too. I don't really like designs wit exposed pilots. I may borrow some ideas from the Aegaks models to create a closed in cockpit as the main body with a "stylised" head section up front.
Finally, I'd like to do something more with the pilot. He doesn't look intimidating enough for me, I think some form of armour is in order.
I may even try creating a slightly larger than minifig scale cyborg pilot with a spaceskull head for the purpose, we'll see, the cockpit design would need to be much MUCH bigger if I did that, which might create a design that is too large for those legs.
this was a learning curve for me. I honestly thought 8 legs would look too crowded, which is why the original only had six. I've also not done many designs using bionicle joints in LDD, so I pretty much had to learn as I built how they would interact and whether there would be problems.
I'm going to add in the comments some notes about possible changes I'd like to make.