[Arm Lock Putting Should Be Illegal]

If you look at Horshel’s grip of the putter, you’ll notice that

the putter if firmly locked on his wrist. Billy is a good player

with a great golf swing. However he challenges Speith in the

whining department. Shut up and play Billy, you can control

only your own play. 

[Arm-Lock Putter Grip and Technique: Unofficial Review]

Yes, this method is good especially if you have a tremor or

Shaky hands. I had been using a standard Bettenardi with a 395g head

And a 35 inch shaft. My pro measured my arm length to my elbow from

the top of the grip, and put an extender in the shaft. 

The idea is to rest the grip on the inside of your left arm (right handed),

holding the putter in your left near bottom of grip. You then put right hand 

On top of left either extending the fingers to grasp your left wrist or grip it over top of the left pushing the grip in a straight line up your left wrist.

It takes some practice but you will develop as straightback and through 

stroke by rocking your shoulders.  Still have to keep head and body still,

but it makes shorties easier.