I only visited the Augustow Canal on the Belarus side in April last year. The Polish side seems like a long drive and little tourist stuff in the northeast (sorry to say) of the country. Saying that, there are probably nice forests but nothing unique or special. Belarus on the other hand has the city of Grodno (still unsure why it's not HrodnA as that's how the pronounce it) nearby and easy access to the canal by a great road system. Only when you get close to the canal do the roads get gravel and unclear signs could possibly lead you onto the wrong road through the forest. Driving past the canal with NO barriers surely is not for the faint of heart, unless of course you are used to driving around in Dutch cities!
I stopped at three places with the pictured Dambrowka clearly the highlight. The first thing I noticed is that the entrance is FREE - wow. Not even parking or someone trying to make a buck of tourists - although that could be different in summer time. The swan pedal boats were also not out because there was clearly nobody vacationing here at the time.
Another bridge you can drive over the canal. Not that great but just want to point it out. There is a cycle track along the canal from Dambrowka all the way to the border which I would probably aim for on my next visit. The weather was beautiful.
As for the uniqueness of the canal, it claims to be old - great - and it was used for a long time. I don't know if that is enough to persuade ICOMOS to inscribe it. The documentation surely lacks detailed information on the unique aspect of the canal at the moment. I still recommend to come here inscription or no inscription - it's a nice place!