I use Olfa cutters. I haven't used other brands so can't give you a great comparison, but I like them just fine.
I have the 45mm ergonomic one (like this:
http://www.amazon.com/9654-RTY-2-Erg...ds=olfa+rotary)
And I also have a 60mm "quick change". I like that on the ergonomic one, the blade is "automatically" covered when you let go of the handle, but I don't find it any more or less kind on my wrists than the standard-shaped 60mm cutter. With either of them, my wrists do eventually get tired if I'm doing a lot of cutting (or are trying to get a little too much "life" out of a dull blade!)
What is unimpressive about this one? Does it not cut well? Feels awkward? You might have a dull blade, if it's difficult to get through the fabric. A nice sharp rotary blade should glide right through the fabric.