I've had a TF-3 for about a week. I really like it!
On balance--the knife is very light. Zytel handle seems nearly weightless compared to one with steel liners and G10 scales. Blade tapers pretty quickly from the pivot and is not as heavy (or presumably strong) as my Spyderco Endura or Elishewitz Stryker which maintain full 0.125" thickness to near the point
On sharpness--Unreal. This is the sharpest out of the box knife I've seen, rivaled only by other SOGs. I've used the knife for packages, envelopes, coffee-bean vacuum pack, and some sundry chores and it seems to perform well here... no brush clearing, wood splitting, or combat yet. The groove really does work--not pure gimmick.
On lockup--quite secure. The locking bolt is similar the SOG's Flash II, but has a pivoting actuatator that gives the user a little more leverage to make release seem easier.
Handle length and thickness are a little on the large side for EDC if you want/need to be discrete.
'Hope this helps.