It's basically what it says it is - a one litre drinking bottle with a straw. My only complaint (and most bottles with straws are like this, to be fair), is that due to the way the straw enters the lid, it's not watertight, so just hoofing it into your bag with the rest of your gear isn't really an option, as stuff will get wet. If you take this to the gym empty and fill it up there, of course, that's not an issue.
I bought it purely because I do Kendo, and on the hottest days, training hard leads to some serious sweating, and if you know anything about kendo, taking a drink with the gear on is impossible with a regular bottle. This type of bottle means a quick glug can be drunk without interrupting the flow of the keiko too much.