My experience is that search and UI transitions are blazing fast. It crashes (rarely, but more than I like) and requires a restart. But I love it and am happy to pay $30/m for it.
Apple's policies permit charging $360/year for that email client, so they do, and that's actually cheaper than many small iOS utilities and games. Since you can cancel any time it is presented as your fault if a small utility, recently worth maybe a buck or two, quietly charges you hundreds of dollars.