1. It all just works. If you’re a regular user of Google — Gmail or Google Apps — this is a dream operating system. The handset requires a Google account to get setup. After verifying your account, your contacts, email, IM and calendar are immediately synched — and stay in sync.

2. During setup, you don’t need to type the date and type. The handset picks this up off the network. Eminently sensible and very smart. I can’t stand having to do this with other handsets such as Nokia. Small but important!

3. The OS locks properly. Just press the ‘hang-up’ button and the device locks until you press the menu button to re-enable. No arsing about with multiple key presses to lock the screen/buttons.

4. The notification system is really immersive. Pull your finger from the top of the screen and it’ll appear to show you new email, texts, calendar notifications and so on.

5. Google Talk IM is brilliant and integrated nicely. New message notifications appear at the top of the screen when you’re doing other things.

6. When you opt to install an application, it gives a detailed overview of what the application is going to use (e.g. ‘access to your personal data such as contacts’).

7. You don’t need an address bar in the browser. You just start typing and the handset interprets this as you wanting to type in a new URL. Very fast to use.

8. Streetview on Google Maps rocks.

9. As well as doing a super job of providing mobile browsing on the go, the browser renders iPhone-formatted mobile pages beautifully (e.g. Facebook).

10. When in Google Maps, I simply begin typing an address and — woosh — I’m presented with addresses from my address book. For example, I simply typed ’3′ and was presented with all matching addresses in a pulldown list. You just start typing. Smart.

11. Another Google Maps point — it is EXTREMELY quick looking up your location. It does this first with a rough estimate based on your nearest cell tower. Brilliantly useful when you want your general location now, not in 2 or 3 minutes.

12. Whilst Google Mail is built-in as standard (and works like a dream), there is also a stand-alone mail client that will work with a whole range of systems. It is EXTREMELY fast with IMAP.

13. SMS messages appear in a threaded list just like a Google Talk conversation. Lovely. Eminently usable.

14. Installing applications is really, really simple. Click install. It downloads in the background and a little notification appears when it’s ready to run.

15. I really like tapping the star next to Google Mail mail messages that I want to remember.

16. The handover between 3G and 2G/GRPS appears fast — at least with my T-Mobile UK device.

Have you got one? What do you like about your G1?