Refrigerated stock is supposed to gel. Its caused by the gelatin you're (intentionally!) extracting from the bones.
To determine if its a success, you'd taste it. Assuming it tastes right, then its a success. If you had you cooked it longer, you may have extracted a little more flavor & gelatin (so it'd be an even thicker gel).
You can also make chicken stock in a slow cooker (if you want an easy way to let it simmer all day), or in a pressure cooker (if you want to make stock in a hour). The taste of these methods will be slightly different, and for best taste pressure-cooker stock requires a non-venting pressure cooker running at 15 psi.