I tried some Stoners car glass cleaner whilst the iMac was on and warm, it was a terrible idea, left it very nice and clean but there was an odd sheen in a few areas if viewed from an angle, ended up buffing it with a water misted microfibre cloth.
Yeah Iklear is nothing but a mess with what they put in their product. Ive found using a good microfibre cloth and DISTILLED water is the best way to clean apple's displays.
I use a microfiber cloth (same as I would use on a modern TV). If it has fingerprints on the screen (after finding and murdering the person that touched the screen) I would dampen the micro fiber cloth preferably in filter water to prevent spotting and wipe it off. Not wet just damp, basically ring out the cloth as much as possible before use.