Next generation is just marketing lingo and "IDS" itself too, as do IPS, NGFW, UTM and whatever they come up with next week. The underlying technologies got several enhancements in the past, e.g. they can look deeper, may use anomaly detection etc - but in my opinion they are still dumb enough and can still be circumvented with not too much efforts.
Don't let you blend from all the marketing claims about 100s or 1000s of applications they can detect or how fast they are and how secure they are. They give you some protection, but not the advertised one.
And in case you don't believe me but the marketing guys you can read here: