We did notice a couple of bugs in the software when it was running on our O2 XDA Zest. The most obvious was to do with the battery icon. Although the main icon did actually dynamically display the remaining battery life, when you tapped on it you were brought to the GSM/3G Networks settings page which is either a bug, or a very strange design decision.
Also, the lock mode didn't lock all the buttons on our device. The left/right d-pad controls remained active when we were running Winterface in full screen mode and most of the other buttons remained active when it was running with the Windows Mobile title bar showing.
The software is also currently lacking some features, such as the ability to add your own back ground wallpaper, and the weather button currently has to be downloaded separately, perhaps because it seems to put more drain on the device's battery. We also weren't overly keen on the way Winterface deals with contacts. It doesn't have a separate menu for contacts, instead you just add your favourites to the grid view. However, if you need quick access to lots of commonly used contacts this can leave you with a lot of pages of icons to swipe through.
Nevertheless, what Winterface has done well is to present you with an interface that really is very finger-friendly. To the best of its ability it tries to avoid leading you to menus with tiny tick boxes or buttons that are too small to be tapped with a finger. Of course it can't stop this happening when you actually enter Windows Mobile applications, but everything that is under its control is easily driven with straightforward finger presses.
For the most part Winterface is a speedy replacement for the standard Windows Mobile interface with a good-looking design and a neat iPhone style layout. There are still some bugs to be ironed out in this new version, such as the battery indicator one we came across with the O2 XDA Zest, but to be fair, the software seems to be updated very quickly. Version 1.3 only appeared in February, but already version 1.31 is out. There's a lot to recommend here, so if your Windows mobile doesn't come preloaded with a touch style shell, then its definitely worth downloading the 14-day trial of Winterface to see how well it works on your device.