I am new to this forum but have been using Caustic 3 on my mobile for the last 6 months or so and wanted to offer a slightly different perspective on what this remarkable application can do.
Over the last few months I have been using free .sf2 soundfont samples to do a mix of different styles of music incorporating electronic but also orchestral and ethnic instruments and have been surprised at the sound quality of what it is possible from a mobile device.
Caustic clearly isn't intended for orchestral composition but I have found that with a little creativity you can produce quite impressive results. I have included a file above which includes 10 tracks all made entirely within Caustic 3 with free soundfonts.
The only features I feel that Caustic 3 would benefit from for the purposes of orchestral music are the ability to automate tempo changes during a track (which Rej has hinted might be feasible in a future update) and some kind of basic keyswitching in the PCM synth (eg. to alternate between legato and staccato samples). And that's about it. Otherwise the only limitation on what you can produce is down to the quality of the samples you are using.
There is something about Caustic that has re-kindled an interest in making music for me - the potential for mobile composition, the convenience of capturing and developing musical ideas at any time, the simplicity and intuitiveness of the interface and the fact that there is no equipment between you and the music - just your finger on one hand and a screen in the other.
I have listened to a fair bit of content created on Caustic on this site, Soundcloud and Youtube and have heard some fantastic electronic and dance music but have yet to really hear anyone branching out beyond this. Perhaps I have not cast my net wide enough but if anyone would like any help or pointers for developing orchestral ideas on Caustic 3 (midi sequencing tips, best .sf2 samples, compositional ideas, etc) I would be happy to oblige if I can.
Otherwise, I would like to again extend my appreciation and admiration to Mr Poirier for his incredible software.