I agree (with qualifiers).
(1) It's an interpreted BASIC implementation so you'll never get the same speed as you do with assembler or compiled BASIC or C programs. Probably not a "big deal" for many apps'.
(2) It forces you to use limited pin functions they define. Also may not be a "big deal" for many apps'.
As you mentioned, the included serial-to-EEPROM program loading process is a big plus since no programmer is required.
I've never used one and probably never will. I suspect they're easy to outgrow as you gain knowledge, experience, and a device programmer (grin).
Mike