by rmsgrey
1) It's worth running through a regular game on the Legacy board so you can remind yourselves how the game works, and/or see the changes made in the Legacy version.2) I've played the odd month "off the books" solo (in particular, we lost both games in May, so I tried a third game without adding any stickers just to see if it was winnable, and whether I could find a working strategy for May's rules before moving on to June). It's a little brain-burny keeping track of 4 characters and all the rules, and having another pair of eyes on the board helps make sure you don't miss anything, but it definitely isn't impossible to manage.
To give some idea of where I'm coming from, I've played XCOM solo with the expansion, on the highest difficulty (and won) and consider that to be marginally easier than Pandemic Legacy Season 1 - largely because you can do more to practice XCOM, while surprises are a key part of Legacy formats, so you need to be more alert to stay on top of all the rules rather than being able to know them by heart.