Although advances have been made, creatine in a liquid form is still considered unstable. You are better off sticking with creatine monohydrate or creatine ethyl ester in powder or tablet form.
Just an additional note on the ATP product marketed by MuscleMarketingUSA: They were fined in 2004 for a violation of New Zealand's Fair Trade Act due to a false claim on the label of their 'liquid creatine' product. It claimed to contain 2500mg of creatine per 5ml serving. Test results showed only 11.5mg. They still market this product.