Sonax is The Best Glass Cleaner...period.
This is the only glass cleaner that I use for personal cars, client cars, and around the house. My wife used it one time...just once, and I had to buy her a bottle. It's not only excellent on glass, try it on hard surface countertops, appliances, you won’t be disappointed. One thing; I agree with Greg, DI needs to have gallon refills of this. Other than that, it’s perfect.

This glass cleaner is far superior to ANYTHING you can get your hands on at the autoparts store or any grocery/hardware place. Smells very good and works like a charm. Would recommend you claybar your glass before using this for the very best results. But even without claybaring the glass, this is great stuff.

I've done a review on this here http://www.detailedimage.com/Ask-a-Pro/product-review-sonax-glass-cleaner/ and have to say this is still a top shelf product. When other cleaners don't work this works! A very little goes a long ways, if you over use it it can smear (just wipe off with a clean dry towel). I hope in time Detailed image can carry just refills of this stuff. Sonax Glass cleaner is one, if not, the best glass cleaners out there

This stuff is incredible! It goes on easy, evaporates quickly and cleans the glass immaculately without leaving behind any residue or requiring much rubbing. It also smells great. I previously used Eimann Clear Vision II and could not get my windshield clean. In particular it would not remove the mineral spots from the hard water that had dried on the glass when I washed my car on a hot day. The Sonax product just cut right through leaving the glass crystal clear. As I said, the stuff is incredible!