After trying out several similar programs (ok,BIAB is a very unique program,but that does not make it necessarily the best) , I have realized a few things about BIAB.
Not everybody will agree,but here's my list of the things I'd like to see in BIAB,and the things I really dislike (ehm,hate ,actually ) about it. Let's start with what I really like about it:

1. It's an invaluable learning tool. Very educative. I am certainly no beginner in the music field,but I always like to learn. I wrote a commercial a few weeks ago by analizying a Django Reinhart tune that was feature in BIAB.
I don't claim that BIAB wrote the music,I take the credits for creating my music (in fact,this feature of BIAB even coming up with a TITLE for the tune,is a bit too much, I think!
But hey,if you don't want to use the feature,no one forces you to,right?'

2. Loads of styles and loads of add-ons. Great choice: there's a bit of everything. Classical,jazz,etc

3. A very good manual,and best of all, a stellar collection of videos,an area that even years ago,
PG Music was miles ahead even compared to Steinberg and Cakewalk,whose absolute disregard for free videos but no disregard for 'passionless' manuals always make me think these people never actually made any music.

3. You can type in the chords ! That to me was a real innovation.

4. VST and ASIO support

now,the things I really dislike about it:

1. The program is overbloated with options. Changing a zillion little things isn't the way.....
I remember that years ago,someone said this,and I disagreed with him. Sorry man! You were 120 per cent correct!

What matter is directness and speed of implementation,and a certain economy in the interface. A composer wants to get to the nitty-gritty. (who has time for everything? There's only time for the most important things. ) I think that people that have to meet schedules,would all agree that a feature is only good if it helps to stimulate inspiration and if it stimulates the user to actually write music,and bypass all the 'wordly' concerns....in other words,I want to carry out whatever operation on the program,in a few steps as possible.

I have used BIAB for years,but did I ever 'explore' all the zillions options? No,I didn't, I had other things I had to learn and deal with : harmony,etc....and I am glad I did

Writing music is ALL that matters. A clean interface stimulates concentration and clarity.
What does a good student does,when he wants to study a certain topic? (whether or not it's music).
He'll clean his desk and get rid of all the distractions. It helps to focus.

The guys at PG Music are great because they try to make their customers happy and they care about their users. It is demonstrated by the constant additions to the program. That's really great,I am not saying 'don't add features' ,but I think they should be added with great care.

2. I don't like the mixer. I don't like these numbers,I 'd like to see a row of SLIDERS and something that looks like a mixer. We want to move sliders,to change the volume,not enter numbers.

3. The Sequencer.....
God. The one on my 1989 Ensoniq SQ1 looked almost as bad. I press Seq,and that terrible little Windows thing comes up. Where are the tracks? I mean,graphical tracks?

4. The intros.....they are really lame. I think that this philosophy about making a program that 'always plays something different when you hit ,again, Play ' is a bit of a limitation. Yamaha arrangers are not as 'interactive',but the intros sound great.
I mean, this 'endless possibility' thing about BIAB always playing something different,is a bit of an illusion. I want to hear ONE intro that sounds great,not 30 of them where all that is happening,are two bars with a tonic and a dominant chord.

Don't get me wrong, BIAB is a fantastic program,and it's not to be compared to other ones,because it does his own thing. But the fact that One Man Band can import Yamaha styles (and thus great intros can be heard -and studied- ) or that the interface in Songtrix Gold is so incredibly 'musical' ,clear,clean ,and 'to the point' make that program have something unique too.
You just click on a bar and you hear the part played by that instrument. It feels like a musician is playing it because you asked. The piano roll shows events separately for each track. In BIAB, i import a midi file,I hit Piano Roll,and I see a wall of notes from all the instruments at the same time.

The mixer in Songtrix looks like a mixer.
BIAB eats Songtrix for breakfast as far as number of styles and add-ons go. The add ons are important....you are given the choice to implement something in the program,but only if you want it.

Also,Songtrix doesn't even support ASIO and VST instruments yet,although I think that the guys at Songtrix are working on it.

But I still love that interface. I wrote more music with that in a week than all the music I wrote in 6 months.

I love BIAB and this post is only intended as a contructive criticism. Obviously I am underlining the criticism more,but BIAB also has fantastic innovations that other programs can only dream about....Realtracks,for example.
BIAB is a great program and an invaluable learning tool....i just hope it will be more direct to use ,more oriented toward stimulating musical composition (I mean written by the user! )
I'd start with a cleaner interface and a mixer....

So what do you love and what you like less about BIAB ?