paperclip works for check engine lights. but a good scan tool can tell you what the sensors are showing which can be very helpful when troubleshooting. obd 1 is really quite basic so a scan tool would be nice for problems that dont throw codes
a connected a snap on code reader to my gt-s when i was in school turns out i had a bad intake temp sensor it was showing over a hundred degrees Fahrenheit. if i go off of a paperclip and i book i would of never known.
obd 1 is very basic only the most important sensors and such are covered the rest are not. i havent bought one myself cause the good ones are costly but im sure owning one would simplify repairs if you know what your looking at and know what the specs should be at.