How effective are the latest treatments for scar removal? What could you recommend?

Improving Scars. Scars come in many varieties, including traumatic, post surgical, hypertrophic and even keloids. Once a scar is present it can only be improved but not completely eliminated. New laser technologies have dramatically increased a doctors ability to reduce the appearance of a scar. You should seek out a board certified plastic surgeon for a consultation for a realistic evaluation of you options.
Many options. It all depends on what kind of scar you are dealing wtih, where it is located, how big it is, how old it is and how it currently looks like. For each scar there are several solutions. It also depends on your genetics for wound healing. But one thing is sure, and that is that a scar cannot be erased 100%, it can only be made less noticeable.
It depends. It completely depends on what type of scar you have and where it is. Sometimes a bad scar can be surgically corrected -- this is best of the scar did not heal properly due to infection or poor technique. If you are unhappy about the color of your scar, a laser may help it fade. If it is too bumpy, topical silicone or a scar cream may help. A steroid injection will often help soften thick scars.
Not very. If you want to remove scars, you usually have three choices: topicals, lasers, surgery. Surgery will take away a bad scar and try to give you a better one. Topicals like silicone or scar cream will soften scars and perhaps make them flatten out, but will never be able to make your scar into "normal" skin. Lasers do the same, but faster by burning away scar tissue so new skin cells can move in.