Oh, so very close!
Quite possibly the best wireless pointing device now on the market, with the lack of a tilt scroll wheel its only shortcoming. Come on, Logitech - you came this far. Please just take it the last few yards and add a tilt scroll wheel. Then its a perfect 10.
I started using Logitech trackballs back in the 80s and continued to do so up until I began using a laptop as my primary computer about six years ago; I have always found thumb-centric trackballs to offer better accuracy and more control than any of their rodent counterparts.
The ONE and ONLY glaring omission that keeps this from being the best Logitech trackball ever, is the lack of a tilt scrolling wheel; Once you get used to using that feature, you really notice its absence; Is it a deal-breaker No; But it definitely leaves room for improvement.