The number one opinion you are going to get is that you should get a Studio 15, or even 17, instead for around the same money.
That being said, I would make the following comments (as someone who has an Inspiron 15 instead of someone who has looked at one in a shop)
- The first thing to get used to is the shape ... the laptop looks slightly odd when it is closed due to the different form factor of the screen, (15.6" 16:9 screen instead of the normal 15.4" 16:10). This means that the laptop is wider than you would expect for it's depth.
- The screen is 15.6" 16:9 running at 1366x768. This is really good for video as its the same resolution as a 720p TV. For normal use the resolution is ok and I have no issues with brightness or viewing angle. I cannot comment on how good it is for gaming as I don't do any. Note that much has been made about the vertical resolution being <800 which is the norm for basic 16:10 laptop screens ... the difference is 32 pixels which is probably less than the height of you taskbar so it's not significant.
- The Inspiron 15 comes with Intel 4500MHD graphics .... so not good for gaming but reasonable for video playback and general desktop use. Personally I wanted a laptop that didn't have a seperate graphics chipset as my previous two laptops have had issues due to thermal problems with their gpus.
- I have the P8400 with 4GB of memory and 320GB of disk. Vista runs rather nicely with it for general use and nothing I have done has given it any problems.
- The blu-ray drive is nice and films look good on the screen. The drive is a bit on the noisey side though. The laptop in general isn't that noisey with the fan noise more of a shush sound than a fan buzz. Speakers are pretty poor though.
- Not much in the way of ports compared with the other Dell models. You get 3(?) USB's and a VGA port as well as the card reader. I have the bluetooth option so use a bluetooth laptop mouse with mine leaving all the ports free.
- Battery life, (with the 6 cell battery I think), is ~1:40-2:00 in general usage.
- Build quality is ok, no obvious issues although I wouldn't want to put to much pressure on the screen.
You could probably find something with the same specification for less if you shop around but it's a nice general use (non-gaming) laptop. Is it worth the money ... well probably not at the moment as it's new so is at a bit of a premium, but I'm happy with my purchase.