I've tried several of these "one for all" type rermotes in the past and could never get them to control everything just right. There was always buttons missing, or functions on my original remote that I couldn't find an equiavelent for.
This Harmony 515 is superb. It does take some fiddling to get it set up just right - it took me 3 sessions totalling a couple of hours until I was finally happy with it.
The PC software you use to program the remote is excellent. You can set up "Activities" like 'Watch DVD' and it will turn on your TV, DVD player and AV Amp and set them all to the correct channels and inputs etc.
You can also set up individual "Devices" - e.g. AV AMP, TV, DVD - and just control them seperately.
If a function for your kit doesn't map onto a specific button on the remote you can add an extra 'button' that maps to the four buttons either side of the LCD panel and the name of the function appears on the LCD screen next to its associated button. e.g. I couldn't find a button to use for my AV Receiver function to scroll through the various DSP modes (SURROUND, ROCK, HALL, CHURCH, etc) so I created one called "DSP". and "Learned" the function from my Amp's original remote. So now, when I select my "AV AMP" device "DSP" appears in the LCD screen and if I press the button next to it then it scrolls through the DSP settings. You can set up dozens of extra 'buttons' in this way so while the remote itself controls the basic functions (volume up/down, channel up/down, play, skip, reqind, etc etc) you can still program it for all the extra less used functions of your various equipment (DSP settings, setup menus, etc).
Harmony maintain a huge database containing thousands IR codes for TV's, DVD players, Amplifiers, etc etc so you will need to know the manufacturer and model number for all your various equipment. The programming software then connects to Harmony via your PC's internet link and downloads all the codes for each device - so you will need a PC connecte to the internet to set this thing up.
Basically, thats all there is to it. As long as you're prepared to spend some time customising it you can make it do exacly what you want.
Believe me, I consider myself to be extremely picky about having a remote control that I can do everything with, and this is the first one I've tried that I can set up to completely replace all my original equipment remotes.
Play.com had it for the lowest price I could find too.
** Review Updated 26 March 2010 **
I've had this remote for a couple of months now. I just want to confirm that its STILL the best 'one-for-all' remote I've ever had.
Once I started using it regularly I found I had to tweak some of the button assignments, but even when I've had to 'teach' it additional original remote functions I've had zero problems getting it to learn from the original remote.
I find the extra 4 buttons by the LCD panel are fantastic for assigning odd functions (like menu and setup buttons for my various bits of kit, or buttons to enter the timer recording menus on my DVD-R).
Just thought I'd confirm my original 5 stars once I'd lived with it for a while. If I could give it 6 stars, I would.