Google apps for your domain has been running successfully for almost a year. We have moved a lot of our clients on to this service especially for their e-mail services. Google apps now also provides IMAP support which is great news for mobile/remote users.
The Google apps Premium edition has a few more features than the standard edition. One huge difference is the space provided on the premium edition which is 25 GB. The other 'system management tools' are not so significant for small businesses but would be useful for companies with many e-mail users on Google apps. See a comparison of the Google apps features between the two versions.
If you move around a lot and need to access your mail on various PC's then Google Apps for your domain is a great choice.
