I was at the expo today (had to cancel my original plan to visit yesterday at the last moment)...Overall, it's quite OK, nothing special to say about it. I didn't see any effect of demonetization as all the collectors and dealers seemed to have plenty of new ₹500 and ₹2000 banknotes.
Only Mumbai mint and a dealer were accepting card payments, rest all were accepting only cash. Like last fairs, majority of dealers were dealing with Republic India banknotes. Plenty of errors/fancy numbers in new ₹500 and ₹2000 notes, plus the star series in new ₹500 notes were available almost with every dealer.
Mumbai mint was (is) selling coin sets for issue price. I was told that dealers are NOT selling coin sets made available by the mint at the counter for less than issue price. May be there was some agreement between them, I don't know. The mint's counter had reasonable crowd and I believe they did a good business.
Hitesh Tahilramani, a well known banknote collector from Surat, has displayed a part of his collection at the exhibition and it's worth visiting. Some extra-ordinary errors, fancy number series notes and varieties are on display. They could have allotted more space for the exhibition, though.
I didn't buy a single coin. Met some fellow collectors, had lunch at Kamat's restaurant (as usual) and also had delicious pasta at a roadside vendor (he's quite popular, I am told). Overall, a day well spent.