Since I have "Kontakt" from NI I say: excellent!

It is all true that MIDI will not transport so many "articualtions" or specific sound for instruments.

The trick of Kontakt to make it sound real: Each instrument has specifics and they can be "scripted". An acoustic bass player might use string one for an F and the same string for a G but another string for an A. This "intelligence" is built into Kontakt. Changing position on the same string will sound different inbetween the notes than using another string. In addition acoustic bass fretless and a part of its "charm" comes from some slightly out of tune notes. Tahts all built in. Next to the excellent samples used.

With this "scripting" technology even a riff recorded from a midi keyboard can sound very convincing "bass-like". Because Kontakt automagically "adds" the queek and noise and stuff a bass would do.

On the other hand: brass licks are still way behind the real thing. Solo brass instruments are so-so... and WAY behind RealTracks.