Like most of the current crop of Windows Mobile 6.1 based smartphones, the DX900 tries to hide some of WinMo's interface deficiencies by adding a more user-friendly interface over the top. Acer has gone for the Spb Mobile Shell, although it's used the older v2.1, rather than the newest V3.0 version of the software. This is pretty much the same interface used on the O2 XDA Zest. We liked it on the Zest and we like it here too because the simple, grid-based menus and minimal graphical animations make it feel very fast and responsive to use.
However, as with all Windows mobiles when you drop back to the standard WinMo interface, the fiddly buttons and fussy menus come as a bit of a shock. That said, you do get the benefits of the Office Mobile bundle of apps for editing documents on the go and also support for multi-tasking - something which Apple hasn't managed to properly implement yet.
The DX900 is built around a Samsung 533 MHz processor, paired with 128MB of RAM. It's not the fastest handset on the block, but it's performance is more than good enough to handle most day to day tasks like emailing, music listening or video watching, although memory can get a bit tight at times. Storage space is also a bit limited at 256MB, but at least you can add extra storage via the side mounted microSD card slot.
As with most of today's smartphones the handset also has built-in GPS. There's no navigation software provided, but the GPS worked great with the free Google Maps app. It was quick to lock on to satellites from a cold start and managed to hold on to them pretty well even in heavily built up areas. Connectivity is pretty good too with Wi-Fi and Bluetooth supported, and as mentioned already there's also HSDPA support for when you need web access when you're on the move.
Call quality is one of the handsets strong points. It holds on to weaker signals pretty well and the ear piece is one of the loudest we've come across, so in noisy environments like train stations it's easy to hold a conversation without saying ‘eh?' every 15 seconds.
Unfortunately on the battery front things aren't so rosy, in fact they're pretty dire. Despite the big, chunky battery the handset struggled to last for more than a day with medium usage of the core functions like taking calls and web browsing. That's very disappointing when most of the latest WinMo handsets are good for around two days. The camera is also a bit of a let down as it only has a 3.0 megapixel resolution, and despite the presence of auto-focus and an LED flash the shots it takes are a bit on the soft side and colour fidelity isn't wonderful.
We love the DX900's dual SIM approach and really wish this idea was implemented on more phones. However, in other areas this handset doesn't fair so well. It's rather large and heavy by today's smartphone standards and the battery life is also a bit of a let down. The latter is especially disappointing as with better battery life it really could have been a useful option for those who need to juggle phones for work and personal use.