During the test period the K610 showed great signal reception both in GSM-only and in UMTS networks. The sound during calls is good and the microphone is pretty sensitive but nothing fancy. The loudspeaker is also loud enough - sorry, pun intended. The MP3 ringtones have the usual sound quality and you can hardly miss a call even in noisy city streets. The vibration is ok, too.
The user interface in K610 is a standard non-smartphone Sony Ericsson user interface. This is the reason why we would use some excerpts from our previous reviews of Sony Ericsson phones. Of course, we would use the screenshots from K610 for illustration and the text would take into account all the interface specifics of this model.
In active stand-by mode the screen displays information about the network signal, battery strength, current date and time, plus the next alarm that's due to go off. You can choose to display the clock with large semi-transparent numbers which take up half the screen but blend with the chosen wallpaper very well as long it's a dark one. The numbers are almost invisible on light-colored wallpapers. A good thing is that you can set the clock to be seen in the upper right angle of the screen even while browsing through the menu.
Pressing the navigation D-pad in any of the four directions can start a given feature or application according to the user preference. In fact when you start using the phone for the first time, the phone reminds you of that option.
The main menu itself is made of a matrix grid with 4 x 3 animated and zooming-in icons. All sub-menus are in listed view with tiny icons on the left side. The phone reacts and performs fast in every submenu and application.
There are several repetitions of applications and shortcuts in the menus, which can be confusing for some users. The test phone had only one preinstalled graphic theme but of course there are more available online. The themes change the color scheme, the wallpaper and supposedly, the menu icons. According to us the default theme is rather irritating. We have seen a version of the phone with a dark purple graphic theme which suited it far better.
One of the things, that have been developed a lot, is the Activity menu which has a dedicated shortcut key on the keypad. The Now running tab of the menu offers real multi-tasking. In K750 you could only run simultaneously one regular application and one Java application, for example. Now you can run three Java applications in the same time which allows for a lot more freedom and flexibility in everyday usage. You can always open the browser, open an instant messenger client, listen to the radio and play a game, all at the same time. That's a great functionality that is not seen in other non-OS phones of other manufacturers. The rest of the functionality of the Activity menu has remained the same - it offers quick access to recent events, the web menu with integrated Google search and the My Shortcuts menu which contains a list of frequently used features and can be modified to the user preference.
The phonebook interface is simple and easy to use. As always, the phonebook asks you whether you would like to copy your contacts from the SIM card to the phone's memory. However you can choose either the SIM contacts or the phone contacts should be the default for the phonebook. Both lists cannot be displayed simultaneously. Otherwise, a nice option is that you can make the phone to autosave in the SIM card any new contacts that you save in the phone's memory.
Switching between different phone numbers and emails for a given contact is possible via pushing the side ways of the joystick.
The maximum capacity of the phonebook is 1000 contacts but you can save up to 2500 phone numbers. Contacts can be ordered by First or Last name. Contacts are searched by gradual typing of the desired name.
When adding a new contact, there are five possibilities for the phone number: Mobile, Home, Work, Fax and Other. This is the first tab of fields for the new contacts. The second one is for email and web addresses. The third is for assigning a picture and a custom ringtone. The fourth goes for Title, Company, Street, City, State, ZIP, Country information. The last, fifth tab, is for additional information and birth date. When you add the birth date, the phone asks you whether you would like to add it to the calendar and put a reminder of it. That's a good feature and we like it that we see it available more and more often in current phones.