largo ostinato

Here's a link to my piece:

https://soundcloud.com/user-659082399-303084762/largo-ostinato

I appreciate feedback.

Technically what's happening: The piece is in 5/4, which gives space to the melodic lines, key of E flat, playing with G natural and flat.  It starts with piano ostinato,  adds a cello ostinato, successively adds 2 melodies and then combines the 2 melodies over the ostinatos.

I created it using mixcraft pro studio 8 virtual instruments.  Feedback on another website was to the effect that real strings on long notes have more dynamics. Do you agree or do you think the more flat, even strings works better?

The entire second section with the cello ostinato isn't very rewarding to listen to. It's super long just like the ostinato and doesn't add very much color. The audience doesn't hear the alto line as an elaboration of the ostinato, just an extension.
The Fb at 1:10 and all times like it is a little bizarre. Playing with the major and minor modes is one thing but altered tonics is a bit strange.
The first melody has a lot of crossed voices issues which doesn't sound very good especially with the close timbre of the two acting instruments.
The piano section was pretty nice.
The overlayed section doesn't quite have the impact you want it to, since there's not any development before hand that makes this feel like an elaborated home space.
I also didn't find the ostinato particularly convincing, as you change the harmonies above it, but never with it.

No thing to add. Just that when you work with this kind of counterpoint, the layers should be clearly distinct (in color and/or tesitura).