Logitech's database already has control info for thousands of devices. If you encounter problems, though, you can also use the 700's "learning" function--assuming you've got the original remote for the product in question. (The software wizard takes you through the process step by step.)
As easy as the remote generally is to use, some users may encounter a few snags when initially setting up their remotes. Often, this will be because of the hardware limitations of older AV equipment. We've had problems in the past with TVs or AV receivers that don't offer discrete input commands, as well as gear with old HDMI connectors that don't easily "refresh" the video connection when switching inputs. Still, we were able to get the 700 to ably control a living room system with a plasma TV, an AV receiver, an HD DVR, an Xbox 360, and a PS3. Add one more device to that list, however, and you'll hit the 700's maximum of six total devices. (We filled the final slot with a Sanyo window air conditioner.) Anyone with a larger system should opt for the Harmony One instead; that remote controls 15 devices. On the other hand, expert users will be happy to hear that the Harmony 700 (unlike the 900 and 1100) does support the programming of custom "sequences," or multidevice macros of up to five steps.
As we said in our earlier reviews of Harmony remotes, if you have a complicated system, you can expect to spend some time fine-tuning the remote to get it to work just right. A certain amount of trial and error is involved. You must verify that the commands work with your equipment as intended, then modify them as necessary. The Web site provides advanced, macro-style options for delay times, multistep commands, and other functions. Also, the remote's Help key helps in troubleshooting by asking natural-language questions on the LCD. For instance, the screen might read, "Is the digital set-top box on?" And Logitech's customer support--both via e-mail and telephone--is, for the most part, very helpful.
From time to time, Logitech offers firmware upgrades for specific remotes, as well as upgrades to the Harmony desktop software. While there's still no way to manage multiple Harmony remotes on the same account (you're required to create separate user accounts, with separate names and passwords, for each of them), Logitech has made it very easy to swap in a new Harmony remote for an old one and transfer in that remote's system setup. For example, if you already had an older Harmony that you use with your main living room system, you could quickly swap in the Harmony 700, and then set up a separate profile for the old Harmony, which you could then use in another room.
As far as actual performance and usage over a one-month period, the Harmony 700 worked flawlessly. Our biggest gripe was the LCD screen; you need to view it straight on, because the colors wash out if viewed from even slightly off angle. Infrared coverage was strong: our gear rarely, if ever, missed a command, and when it did, quickly stepping through the Help menu resolved the issue. Just remember that the 700 lacks any sort of RF (radio frequency) support. If you need to control gear that's outside your line of sight (in a cabinet, for instance), you'll want to trade up to the top-end Harmony 900 instead (or at least consider one of Logitech's IR extender kits). Also, PS3 owners will want to spring for the Logitech Harmony Adapter to control that console via Bluetooth (since Sony inexplicably left an infrared receiver off its game console.)
In the final analysis, the Logitech Harmony is a superb universal remote that's being sold at a very competitive sub-$150 price. If you need to control only six devices or fewer, and you don't need RF compatibility, it's an easy recommendation. That said, just be sure to check the price of the Harmony One first--it's still the preferred model, and well worth buying if it can be found within your budget.