We finished the Trent in August of this year. Absolutely great and would do it again.
Yes, it can get busy on weekends, especially around the "rental houseboat area" Buckhorn, Bobcaygeon, Fenelon Falls however they are wonderful areas. Lots of great areas before and after the locks, close to small towns, shops, restaurants,
Lock masters are great and easy to get thru. Prices already mentioned, but not bad.
Some things more, some less. Alcohol and fuel are pricey. Exchange rate is excellent and restaurants reasonable.
Overall, the absolute highlights of my loop trip have included the Trent Severn, Georgian Bay, North Channel and the Erie Canal. I'd repeat any of them.
Still need to do the Tom Bigbee down to Mobile and along the coast over to St. Pete.