Yes, I use I2C, but PBP's I2CREAD and I2CWRITE and not the chips hardware module. Everything is fine as mister_e suggested. I also use internal EEPROM READ/WRITE also from PBP on this chip, again no problems with that either. The Timers work too and so do the ADC's and the pwm modules as I mentioned earlier. But on the negative side, I can't vouch for any hardware components I've not listed. The Labour and Parts saving in not having to add a Resonator or Xtal is worth the the few cents extra. I have about 100/day of the 18F2420 (and the LF version when earlier we couldn't get stock of the straight one) going into the field, with the first units being shipped at the start of the year - nothing's bounced back. This is a major product badged for a blue-chip company that earns me big-bucks in royalties, I wouldn't risk that on a suspect PIC.