Sorry Huevos about Baron Munchausen - it's just one of those Gilliam films that I think is massively, massively under-rated. I'd go as far as to say I prefer it to nearly every film on your list, and would give it a solid 8/10. 5/10 is average, because it's halfway between the worst score and the best - otherwise you only really have 8, 9 and 10 to differentiate between different levels of 'good', while most of your scoring range is reserved for specifying exactly how bad something is (and lets face, that doesn't matter half as much).

75% average is ok when you're marking the work of schoolchildren, because getting too much wrong is simply depressing in an exam situation. But for reviewing films, music, games, books etc. it's one of those pet hates of mine.

Returning to the question of what I'd rate Mr. Williams' other work, The Fisher King gets a 9, Toys a 6 as a guilty pleasure (besides, it has Joan Cusack in it, and I've never disliked her in anything), Insomnia a 6 or 7 (depending on whether I can ignore the superior original or not), and then everything else would either struggle to get a 5, or I've not seen it in so long or at all, and don't feel qualified to comment.

On the subject of Steve Martin, I've never really been a fan, sorry.