Hello,
I don't like to use capitalization in titles. I never use Widget Product Reviews or WIDGET PRODUCT REVIEWS, but Widget product reviews because it is the correct way in my opinion. Looking at the new data published by Google via Webmaster tools I have a feeling I could improve my CTR using one of the two capitalization methods. Also, looking at the serps, capitalized titles do seem to stand out a bit compared to non capitalized.
What do you think? Do you use non capital, First Letter Caps or ALL CAPITALS?