I have just recently upgraded to Sibelius 6. I will be able to report in more detail later but for the moment, it's looking really good. I'm especially liking that there is now a feature for moving a single word or syllable slightly left or right if the text for the lyrics happen to crowd a little too closely to each other. I find Sibelius to be very user friendly. However, I have not attempted advanced work beyond my own SSAATB (with organ) chorale so I am unable to state, in terms of music engraving, whether this software is 'perfect.' Also, Sibelius 6 has new features for composers that are very, very appealing - such as now being able to work with and compare 'versions' of one's score(s). Finally, the sound tones are so very 'on' that I find I want to begin creating tunes instead of just 'typing notes!' So - in two words - it's fun!
the music that you hear that sounds 'real' are not done from a notation program, but rather with a DAW and massaged, every scrap of nuance accounted for. Notation program = for making parts, one way to write a score and hear *something* back immediately. DAW (Digital Performer, Logic, Cubase, etc) is for recording midi and audio performances and for fine tuning them. And they are used in conjunction with sample libraries and vst instruments, like Vienna Symphonic Library or EWQLSO. Each library has certain nuance to learn to make it sound more realistic. And understanding the ins and outs of programming with your libraries as well as solid fundamental understanding of orchestration is all part of the modern composer process. Personally I use Finale 2010 and Sibelius 6 for notation, but I only use these programs to make parts for live sessions. I write by hand on paper sketches, then sequence in a DAW, then dump to Finale to create a score and extract parts