Grammer 2 (Application) is the innovative interpretor that could easily replace TI-BASIC.
I don't see why not people should not use Grammer 2. Unlike the previous version, Grammer is an application, which means that you don't have to worry about random reset deleting Grammer. Also, with shiny features such as fire effect, tilemapping, memory access, etc., Grammer is really powerful interpretor! I just wish that it could support multiple keypresses, though.
With the "Full" mode (just like Axe), Grammer programs can be run at amazing 15MHz speed(Of course, the 15MHz limited to 84+SE. Considering that this is an interpretor, it's pretty darn fast!
Learning Curve: 9/10
Of course, this is bit harder than learning TI-BASIC. However, Grammer is easier to learn than Axe or ASM.
Total - 28.5/30
Learning Grammer is worth a try. :)