I’ve just finished my second solo game, mainly just to learn the rules before I play a human. They work very well. The cards mostly act as command points but you have special events that come up and let you do an extra cannon bombardment or a special volley fire etc these can make you suddenly change your tactics, or open up new possibilities of attack, which makes a surprise. Sometimes missing in solo games. The cards can be a bit gamey, but I found it lots of fun, if not actually a simulation type game.
They are worth a go for solo play I think.