I've had my Harmony 550 since Christmas and have grown to love it. It controls each of my components in every way I want giving me a truly universal remote. The sleek design and small size is something I liked from the beginning. Because of its size and button placement it did take a while to get used to it and I even considered exchanging it for the 670. Now I'm glad I didn't. The 670 is advertised to be especially good for DVR (PVR, Tivo) replacement and that was of real interest to me. However, I've been able to program the 550 to control the DVR portion of my STB and all is wonderful.

The only characteristic of the 550 which is taking some getting used to is the size of the buttons, especially the numbered ones. I often change channels using the numbered buttons and since they are located at the bottom it's natural for me to use my thumb. Because of the smaller size and location it's taken a bit of getting used to and occasionally I'll miss "dial" a channel. This was a real concern for me the first week or so, but I'm slowly becoming accustomed to this. In the end the size and style of the 550 is really appealing to me and that overcomes the button size and placement.

It also occurred to me that since I had used the "universal" remote which came with my STB for over 3 years, changing to any new remote would take some getting used too. I have no doubt that before long I can work with the 550 blindfolded just as I could with the other one.

I should mention that the software was a bit unusual and it took me a while before I really understood it well. I did work for me with no glitches at all. Also, I called Logitech support with questions a couple of times and found the wait time was never longer than about 5 minutes. These were daytime calls so I can't speak to what it's like in the evenings. The level one support answered all my questions.

Panasonic Plasma
Dish VIP622 STB
Samsung DVD
Yamaha A/V Receiver
(as you can see I'm brand loyal :)