I have had the X1 since its release date in the UK via a contract with O2.
The phone runs Windows Mobile 6.1 with a customised 'Panels' interface.
The X1 comes jammed with many default programs such as Microsoft Office, MSN Messenger and other applications oyu would expect to see on the phone. There are also a wide range of other programs that are either free or you can pay for. Some fo the free applications are things like Facebook and Google Maps, however I regularly use TomTom satnav on my phone.

The touchscreen is fairly responsive but the use of the qwerty keyboard is a bonus with this phone as it makes replying to messages so much quicker.
Having never used Windows Mobile before it did take me a while to get used to the phone and all the setting available but once you understand how it works you realise its very simliar to Windows for your PC.

Once problem I have had with the phone is it is not very rugged. I dropped the phone from a small height and the plastic has cracked, however O2 quickly sent me a new one. Since then the phone has had a bit of a beating like all phones do and unfortunatly the X1 hasn't taken too well to it. Various number of scratches and cracks have appeared on the phone, but since my contract is nearly up and they are not affecting the phone in anyway I cannot see the point of returning it.

This phone is one of the "always on" for internet phones so its best to get the unlimited internet package. I have mine setup to recieve emails, gets tweets from twitter, download the latest weather etc.
The screen is fairly large however it has a very good resolution. As long as you are in a 3G area or have the phones Wifi turned on then the internet browsing is fast and you can stream from YouTube without a problem.

As with all my phones I like to make them different so I have flashed a custom firmware package to the phone from xda-devs so my X1 is now running the same software that is on the new HTC HD2.