- palm sits underneath the fretboard - decreases mobility and ability to stretch
- fingers flatten out when playing notes on the sixth and fifth strings - fingers will likely come into accidental contact with strings, causing muffled notes, or "dead strings".
It should be noted that at some point in the future, you may actually use your thumb to wrap around the neck of the guitar, to fret notes on the sixth string. You may also notice that some of your favorite guitarists grip the neck in a manner similar to the one illustrated here. It is a hand position that can be effective in the proper situation, but it will make learning the guitar much more difficult. Avoid it for now.