My first detector was the 705 it is quite an investment if you are not even sure you will like the hobby. However if you have an addictive personality it is the right choice! It took me a while to use it and the first year I dug every signal, just because I wanted to learn. I love the auto ground balance and the 4 preset programs, plus you can tweak those programs to accept or reject a target that you want to include or eliminate. I have been detecting only for 3 years and I am still learning! I don't read much because I don't retain much... (LOL) but I was able to learn a lot by trial and error. I am still learning, so I can't say I learned quick, but If I can figure it out anybody can figure it out! If you can afford the extra $ I would go with the 705.
Good Luck!
Cindy