Just spent some time with the Polytune. I agree, compared the the TU-2, it is a great tuner (almost any tuner is better than that old dog IMO). Nice unit. Nice quick tracking, 'OK' accuracy. The 'polytune' function seems pretty useless for Bass Guitar... I find that the tracking is slow on that function, and strings that show out of tune or in tune do not necessarily correlate to the readings you get on the 'individual string' tuning. So, pretty useless IMO (again, at least for bass).
It is IMO not in the same league as the REALLY fast and ridiculously accurate, smaller, and more ruggedly built Sonic Turbo Tuner (it would take most much less time to just tune each string with the Sonic than using the 'polytune function').
However, nice unit, and more in competition with the PitchBlack unit... nice tracking, 'good enough' accuracy, decent construction, and vastly superior to a tuner like the TU-2. The 'polytune' function is fun, if a bit useless.
IMO and IME.