Sideways writing is not ideal. It's fine for things that you can physically rotate like books and magazines, or even digital documents, but on something like this, it's difficult to read, especially for people with disabilities. I work in branding and communications and those are the conditions that we're emphasizing vertical text on our new guidelines.
I know people in this forum are derisive on wayfinding, communications and design professionals like myself, but there are lots of considerations that don't always seem obvious to a railfan. Text on white is always the best, with high visual contrast (and yes, that means the TTC map is not great!). The sign is about an average person height, which means it's in the sight line of most people; making it larger would mean people would have to stop and strain, as opposed to a quick glance. Also, it doesn't help that we're judging this from a picture that's across the road, as opposed to right in front of us. Designers often print out signs in their offices; I recently had to make a new sign and printed out multiple versions and physically showed it to people.
Vertical maps like what has been added to the platforms are pretty standard for rapid transit lines. They look very similar to the London Underground maps that you see upon entry to the platform.