Summary: This is one of a small number of wireless headsets that is self-contained, meaning that there's no belt pack with a wire to the headset, and among those the only one I know of that does not require a handset lifter. That makes it my first choice. However, it only works on standard phone lines, so it won't work in many offices.

Using a headset with a belt pack is a nuisance. For example, when answering you have two parts to pick up. Similarly, handset lifters should be avoided when possible, because they can move around and be unreliable, not to mention all the parts and wires on your desk. Avoiding these problems is a big advantage.

On the other hand, the CS55H could be easier to use. Answering is no problem, but dialing a call requires extra work, because a separate phone is required and you must handle both the headset and the phone. In particular, after dialing, you must hang up the separate phone. If you get a busy, you must remember to hang up both. These may seem minor, but I find them a bigger nuisance than I would have thought.

I don't know why Plantronics didn't add a dial pad. This would have made it easier to use and eliminated a bunch of wires and an extra phone on your desk. The separate phone should be optional.

Summary: If you are in the market for a cordless headset for home telephonics, your choices are very limited. Plantronics CS55H is, for now, the sole game in town for a home phone cordless headset-only system. It is based on the Plantronics CS business line of cordless headsets, and in fact it is a clone of their CS60 model (though configured for home use.)
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Out of the box, the CS55H includes the cordless headset, charging base station, power adapter(AC120v->DC9V@500mA), headband, assorted earloops, the \"home phone adapter\" PSTN module, and a phone jack splitter. This product is designed for users who primarily answer incoming calls, and/or who have access to a separate phone to place outgoing calls; there is no dial pad. If you prefer a headset with a dial pad, try the Plantronics CT-12 (not recommended for use with Wifi), Plantronics Calisto, or the RCA ViSYS (not recommended for use with Wifi).
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The CS55H headset has a claimed range of 300 feet from the base station. But the range is reduced in the real world by metallic obstructions and home barriers such as walls, floors, doors, and windows. Fortunately the CS55H operates in the 1.9Ghz spectrum, which should allow for slightly better signal penetration. And the frequency of this device ensures no interference with WiFi and BlueTooth hardware and other cordless phone devices.
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The headset has a volume control as well as mute and action (for answering/disconnecting calls) buttons. There are audible and visual indicators for low battery alert and charging functions. It also has built-in noise cancellation, and according to Plantronics uses \"64-bit digital encryption\" for privacy (though this is not documented in the owners manual.) Thankfully the headset includes a user-replaceable rechargeable battery. The unit takes about three hours to fully charge.
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The included earloops allow for a range of ear sizes; unfortunately even when sized properly, during extended wear the headset's over-the-ear position can be be uncomfortable. The earloops also seem marginal in their ability to hold the headset in place. The over-the-head headset attachment is recommended for longer or mobile periods of use. Though awkwardly large compared to many BlueTooth headsets, wearing this headset can quickly feel natural.
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Perhaps most importantly, the call quality with the CS55H is very good. Calls sound very clear and are static free. Callers report hearing great voice quality with minimal background noise, better than from some corded handsets.
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So who is the CS55H for? If you are someone like me who is constantly on the go around the house and/or spends a lot of time on a land line phone and needs hands-free communication with good coverage range, the CS55H might be the way to go. Equally if you use WiFi or BlueTooth hardware and need a high quality interference free noise-canceling cordless headset solution this might be your answer. If you need a low cost, VoIP or Mobile phone solution, look elsewhere.
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Note that the list price ($329.99) of this unit seems high for what you get. Maybe that is due in part to its relative uniqueness in the marketplace. Discount pricing should be easy to find through shopping comparison search engines and from physical retailers. Online CS55H pricing currently varies by more than $100, so a little research could result in substantial savings.