illender

Played until about the end of c6. Will the classic server be like the old days or are there a ton of differences?

I played warlock for many years until about c6ish. im returning now after a long break and going to start in the classic server. has anything changed with pets such as which one to lvl with or grind with? I could have swore before that kai took too much of your xp so it was only for pvp. any info on summoner changes is appreciated.