Yes, it's acceptable, is more readable, and is less expensive (faster) than calling $(this).val().
Simply put, $(this) refers to a jQuery object, whilst this refers to a DOM element.
The FAQ here touches upon it briefly (under 'Know Your DOM Properties and Functions')
You should use plain "this" when the native DOM APIs suffice, and
  $(this) when you need the help of jQuery. 
I'd also suggest reading the following:
$(this) vs this in jQuery
jQuery: What's the difference between '$(this)' and 'this'?
When to use Vanilla JavaScript vs. jQuery?
utilizing-the-awesome-power-of-jquery-to-access-properties-of-an-element
this demystified