The Dake's Annotated Bible says that it is King James, but I was wondering if it is a good study Bible to use?

The Dake’s Annotated Reference Bible has many unique and original notes that can be helpful to the student of the Bible. About 40,000 are sold each year. Therefore, as a second or third reference Bible for the Bible student who is established in the faith and has a good grasp of Bible doctrine, it is an acceptable choice. However, as a primary study Bible or for use by anyone who is still learning basic doctrine, it is a bad choice because it will lead the student toward false doctrine in certain places. Also, the user of this Bible should know the history of its author.

Finis Jennings Dake (1902-1987) was an Assembly of God preacher and was prominent in Pentecostal and charismatic circles. Among other things, he claimed to have received a special anointing that enabled him to quote hundreds of verses without having memorized them. In 1937, he was convicted of transporting 16-year-old Emma Barelli across the Wisconsin state line “for the purpose of debauchery and other immoral practices.” He pleaded guilty and spent the next six months in a Milwaukee jail while writing a commentary on the Bible. He soon moved to Cleveland, Tennessee, where he spent much of the remainder of his life as a pastor in the Church of God and then as an independent Pentecostal pastor. As to recommendations, Jimmy Swaggart wrote, “Finis Dake was a scholar unparalleled. I owe my Bible education to this man.”

The notes in Dake’s Bible will support Charismatic gifts such as tongues and the requirement of works both to get and to keep salvation. For instance, in his note on 3John 2 he gives three kinds of blessings that are God’s will: material prosperity, bodily healing and health, and soul salvation. He states, “If any one of these blessings was not the will of God, would it be the wish of this most beloved apostle? If such blessings are the will of God for one man, they are for all men alike who will have faith for them, because in the gospel there is no respect of persons.” This is what is commonly known as the health and wealth gospel of the Charismatics. Unfortunately, it is unscriptural and it makes Paul to be faithless and out of the will of God.

Another example of doctrinal problems can be found in the note on John 10:26But ye believe not, because ye are not of my sheep, as I said unto you.
See All.... Dake gives three things men must do and continue in to receive eternal life: believe, hear His voice, and follow Christ. Of following Christ, he states, “not only at the beginning of a Christian experience, but daily and throughout life.” This is a works salvation doctrine that requires continued faithfulness in order to “receive” eternal life. This is one of the teachings found throughout Dake’s Bible.

There are other problems as well, but this should give you the idea. If you want to know more, I suggest the article in Christian Research Journal, Volume 27, Number 5 on the Dake’s Reference Bible. Many of the details in this answer are taken from this article.