How many novels this author has written!

[Mori]

Is the following exclamation grammatical?

John: 50 novels? Wow! How many novels this author has written!

 

[emsr2d2]

It's grammatical but it sounds a little old-fashioned (to me).

 

[Tarheel]

More natural. (See below.)

50 novels! Wow! That's a lot! That's one prolific author.

 

[Rover_KE]

As an exclamation rather than a question, I'd say 'What a lot of novels Barbara Cartland has written!'

 

[teechar]

That's one prolific author.

or "What a prolific author!".

 

[Tarheel]

or "What a prolific author!".

Yes, but I already had used three exclamation marks. All by itself, OK.