I am Thinking of buying HD. Mostly will use it for modeling.
How is modeling in hd?
I have used wings, 3ds max, xsi, blender.
How does it compare, I dont want to waste my money.

you don't need to buy it if you just need to model
Apprentice is free and there is no difference in modeling tools comparing to HD (and both are non-commercial so no difference there either)

so try it for free and if you like it and want to render without watermark, you may consider buying HD

there are lot of questions about modeling and comparison to other apps on this forum and on od-force, just use search

what about export?
Can you export from the free version and if so what format?
I prefer to uv map in a standalone app.

you can export in many fomats except fbx in apprentice or HD

http://www.sidefx.com/index.php?option=com_content&task=view&id=589&Itemid=221 [sidefx.com]
http://www.sidefx.com/docs/houdini11.0/io/formats/geometry_formats [sidefx.com]

thank you very much for your speedy reply.
I have downloaded and will give it try.