It is an altcoin, but unlike most altcoins it has a shared history with Bitcoin. Basically, at the moment of it's creation (today, August 1st), everone who owned bitcoins owned an equal number of Bitcoin Cash. So now they are two separate coins and two separate chains, but with a shared history.
> Is this a good thing or a bad thing?
It's hard to give a judgement. When Apple started working on a self-driving car, was that a good thing or a bad thing? Hard to say, it more of just was a thing to know, unless you had a horse in the self-driving car race. Bitcoin Cash will either be successful in some capacity or it will flop altogether, but the original Bitcoin certainly isn't going anywhere.
If you don't have a horse in the race, I wouldn't think of it as a good or bad thing. It's just an event that doesn't mean too much unless you are excited about Bitcoin Cash and the principles it stands for, or if you have Bitcoin and don't realize that you also have an equivalent number of Bitcoin Cash (currently trading at like $200 each - a nontrivial sum!)