I use the Besta CD-606 and love it. You can set it for a number of popular input methods, including (most importantly for me, that is) Hanyu Pinyin and Radical-Stroke. I’ve been using Bestas for years because I find their quality and ease of use the best.
It’s not without its flaws. For one, after you look up the meaning of a phrase, pressing the escape key brings you back to the original dictionary entry screen rather than the previous screen you had been looking at. It means that you have to re-input characters if you want to look again at the list of words beginning with that character.
In addition, I’ve found some flaws in definitions and even a few spelling mistakes.
Also, the keys aren’t sensitive enough for really rapid input, but they are more sensitive than my last Besta, the DC-67.
Also, a feature older versions had, which is missing on this one: if you entered a character with the wrong tone, pressing an arrow key would display characters with other tones. This useful feature is not present in CD-606 as far as I can tell, meaning that if you input the wrong tone you wuill have to re-enter the character.
Still, this Besta blows away anything else I’ve ever seen.