In my general encounters watching Frank on TV I’ve found him sometimes funny, sometimes grating.
He is a talented comic, but his impressions are more about exaggerating several trademark gestures or vocal inflections of the people in question, he is by no means able to do an impression to any deeper level than that as far as what I’ve seen of him.
Sometimes he can be irritating (his Jerry seinfield is exhausting to watch)
But sometimes he can be pretty funny.
Below is a clip from an appearance on Conan which was a mostly succesful comic bit for Frank.
Just give it a few seconds and the survey note goes away, the video plays cleanly after that in high quality.
[youtube=http://www.youtube.com/watch?v=v0GAjMpMZKg]