OBDI vs OBDII

I recently bought a 97 miata for a very good price 4,400, then i talk to my friend who always like to look up the potential of my cars and he said you should of got a 95 cuz it has the OBDI unlike my 97 with the OBDII..

so if anyone could tell me the pros and cons of these OBD'S and if its really that bid of a deal??

any info would be great.

thx in advance