to siena park unit owners, pano magcommute papunta doon? Is it really walking distance from Sm Bicutan? 
I can answer this as my girlfriend and I walked from SM Bicutan to Sienna Park a few months ago. Yes it is true that it is a short walk (10-15 mins IIRC) from SM Bicutan to the gate of Sienna Park. I would like to point out some things though.
1. No proper sidewalk to walk on. Sometime you will have to walk on the road itself.
2. I wouldn't walk at night, not too sure if it's safe.
3. As i said in the earlier post, the walk from the gate to the first buildings in Sienna Park is quite long and the last time I went there, there was no shaded walkway

So the walk from SM Bicutan to your unit could be quite tiring if you're not used to walking long distances.
Some pics (these are about 2 months old haha)
1. The gate and manong guard.
(http://i.imgur.com/AV4X1.jpg)
2. Taken just after passing manong guard. Notice there are no sidewalks and no shade. Also notice the sharp curve at the end.
(http://i.imgur.com/3stId.jpg)
3. This pic is taken just after the sharp curve. The building at the end is Lilac.
(http://i.imgur.com/IA5x7.jpg)