Intelligibility / comprehensibility (2.2.1.1.1.2/180) - how intelligible is the output under different conditions (e.g, are the sentence fragments translated while being entered)
Dialogue - does the system support rudimentary pronominal reference and other multi-turn phenomena
Changeability or extensibility (2.2.5.2/213) - can the user dynamically add new words and phrases to the lexicon, and with how much effort.
Non-textual pragmatic content - how well does the system handle emotive words and other marks, such as smiley faces, unusual spacing, etc.
Reliability (2.2.2/600) - how reliable is the system; if it breakes, how easily can the repair be tested, how does it behave on encountering unexpected or erroneous input, how does it behave when it crashes, how often does it happen, how difficult is it to restart.