I was there last year and had a great time.
Vichy is a lovely city but seems to be disliked by the French because of its wartime connections. Its bordered by a large lake which they were using for seaplanes/amphibians so that was a plus.
There was a shuttle bus into the town. About a 90 minute walk otherwise (ask me how I know!).
The flyin itself was very good with small flying displays in the afternoon.