Should I use Upscaling for my PS2 games on PS3?

 
When I use Upscaling, I notice that the options when I press the PS button look like that of a PS3 game, which means it looks nice. when I have it off, teh letter of thsoe options are big and take up alot of the screen when I press the PS button. is it a good idea to use Upscaling if I have a 720p HDTV? should my display settings be set to anything when palying PS2 games upscaled? (like should I have 720p and 1080i checked off, because technically my TV supports both, or just have 720p checked off, because I think thats my TVs native) Having the upscaling set to full dosent seem to streatch image in a bad way, meaning im not losing text or picture because its too zoomed in.  will it really make games look better and not blurry?

Test it and see what works for you/your TV? People can't tell you what looks good for your eyes...
 
If your TV's upscaler is better than the PS3's, then it's best left to off, if the PS3's upscaler is better than your TV's, set to on.

So, try with it on, and off, and see what looks better to your eyes. In regards to the actual game, not the menus. Then, use that forever.