The Logitech Harmony 510 is the replacement for the Harmony 520, which is being discontinued. Except for a slightly different color scheme (silver on black instead of black on silver) and the addition of four color-coded buttons below the keypad, it's essentially the identical unit. The catch: Logitech cut the number of devices the 510 can control to just 5 (versus 12 for the 520). Thankfully, two other Harmony models--the Logitech Harmony 550 and the Logitech Harmony Advanced Universal Remote for Xbox 360 (AURX360)--remain available in Logitech's line. All four models are almost identical, but the 550 and AURX360 both have more buttons and control more devices than the 510--despite being available for a nearly identical sub-$100 street price. And that's pretty much the bottom line here: either one of those would be a better choice than the 510. (If you've got a bigger budget, the Harmony 720 or, ideally, the Harmony One are even better choices.)
With that caveat in place: if you're still interested in the 510, read on.
The Logitech Harmony 510 crams a good number of buttons onto its modest frame, including a complete numeric keypad, a four-way directional pad, and full playback transport controls. The functional highlight of the 510 is the backlit LCD display. Flanked by four programmable keys that you can label differently on separate pages, it allows the Harmony to emulate even the most esoteric buttons as well as engage activities and macros. For the most part, the overall button layout is a pleasure to use, but we lamented the somewhat mushy rubber buttons and felt those on the numeric keypad were a bit too tiny and grouped too closely together, which sometimes caused us to misdial our channel changes.
The Harmony 510 uses four AAA batteries. We would've liked to see a recharger dock, such as the one found on the upscale Logitech Harmony models, but that's probably too much to ask from this entry-level model. Instead, you'll probably want to invest in a set of third-party rechargeable nickel-metal-hydride batteries.
As with all Harmony remotes, you add your devices and set up Activities using a computer-based interface (the remote is both Windows- and Mac-compatible). All Harmony remotes boast compatibility with more than 100,000 devices, and when we fired up the software and scrolled through the company list, we didn't see any reason to argue that bullet point. The scope can be a bit daunting for beginners, since there are a few dozen component types listed, such as TV, AV receiver, and DVD player, and hundreds of manufacturers within each one of those. Thankfully, the software is pretty forgiving, and as long as you have the company name and model number, it should be able to cull the commands for your product.
On the off chance that your device isn't yet in Logitech's database, it will try to find a close match (a similar product from the same manufacturer). Otherwise, you'll need to "teach" the Harmony commands from your existing remote (point the old remote at the Logitech's IR sensor, and follow the on-screen instructions). If you have a complicated setup, you might end up calling Logitech's customer service department for advice. However, most tech-savvy users will probably find it to be a pretty straightforward setup. Also, Logitech offers regular updates for both the remote's firmware and its PC-based software, so everything's generally up-to-date and relatively bug-free.