Two of my three TN's were done in person at the Peace Bridge POE and both times were good experiences. The first time my TN was adjucated by officer Sam Tirrano who was very friendly, knew what he was doing and approved my TN in about 20 minutes.
The second TN (I did back in July 06) wasn't a bad experience either. My offer letter was missing a brief statement and I needed a copy of my employers P.E. (Professional Engineer) certificate to prove that I was indeed working under direct supervision of a licensed engineer (as is the requirement under the Sci. Tech category). The officer, while not smiling cheerfuly happy, wasn't bad either and allowed me to temporarily withdraw my application, gave me the Fort Erie POE fax number, call my boss and get my employer to quickly rewrite the offer letter and fax it to the POE that same instance at which point my TN was instantly approved.
My third TN was done via mail so that don't really matter for this thread.
Also, I have re-entered the U.S via the Fort Erie POE on a bunch of occasions using my valid TN's and have NEVER had a problem. Overall Fort Erie Peace Bridge POE is a good POE in my experience. It shoul dbe known that my TN application packages were very straightforward (even for the Sci. Tech category) and my application & documents were prepared relatively well by myself. Just make sure yours is too.