Having taken my own advice about getting the best upgrade deal on Vodafone, I am now the proud owner of a Samsung Galaxy S II. I'm still in the first 24 hours of use, so here are my first impressions of the phone and the differences I have noticed since moving from my old HTC Desire.

The S II is fast. Really fast. Applications install quickly, downloads blaze away and everything pings into view quickly and smoothly. The HTC Desire was no slouch, but the S II shows how things have really moved on in the last couple of years. Because of the shape of the S II, being a thin slab with rounded corners, it can sometimes be hard to know which way up it is when the screen is off. I have already picked it up upside down in a darkened room. It fits in the hand nicely, just about, although it may be a bit unwieldy for those of a more dainty frame. The textured back, incorporating the "it's so thin I'm sure I'm going to snap it while taking it off" cover makes it easy to grip on to and feels nice. The touch sensitive menu and back buttons at the bottom of the phone work well. I thought they might take longer to get used to after using hardware ones for so long. The fact that they are the right way round, menu on left, back on right, unlike some phones, such as the Xperia Arc S, is a bonus. The build quality of the S II is very good, giving an overall feel of a quality device.

I found the display a little dark at first, compared to the Desire, but maybe I just had that screen on too bright. Anyway, a bit of tweaking of the brightness can sort that out. However, I cannot find a way to have the automatic brightness setting on, so the S II will adapt to ambient light, with the default brightness set to a custom level at the same time.

Have no fear if you ever lose your S II or have it stolen as it supports the excellent SamsungDive service. Once registered and activated on your phone, this allows you to find your phone, lock it and wipe it remotely via a web interface. The phone also supports the Android Backup service, which backs up the phone's settings, apps, etc to the cloud.

The S II is advertised as having 16GB of storage. What you actually get is 11.5GB of USB storage and around 2GB of phone storage, depending on what default apps etc your network installs. Having two types of storage inside the phone is a bit confusing at first as it's not obvious what the S II will put where, but it seems to be intelligent enough to decide where to save media and apps. With the option to add an SD card as well (I picked up a 16GB one for a steal on Amazon) there is more than enough memory available for even the most demanding user. Indeed, after the cramped confines of the HTC Desire it feels positively agoraphobic, with my apps and media banging around in a cavernous digital warehouse.

The TouchWiz interface that Samsung overlay on Android is much less conspicuous than HTC's Sense. In fact, it feels like a stock Android device. I thought I might miss Sense more than I have so far. The keyboard is basic and functional, but nothing special, so I have replaced it with the far superior SwiftKey X. One little gotcha; text on webpages would flow, to fit to the screen, by default in the HTC browser, but you have to turn this option on in the S II browser. Surprisingly, the S II has only 5 options in the wallpapers gallery, which I thought was a bit stingy to say the least. There are a couple of junk Vodafone apps pre-installed, but that seems to be the norm these days.

I have missed the trackball from the HTC Desire a bit. A few times I have found myself moving my finger over the bottom of the S II expecting the cursor to move on the screen. Also, the SII does not have a dedicated hardware search button, as the Desire did, and there have been times already when I have reached for it. You can bring up Google search by long pressing on the S II's menu key, but this doesn't seem to work in all scenarios, such as being in a phone settings menu. Strangely, the S II has no notification light flashing away green to tell you that it has a connection or orange when charging. Consequently you cannot tell if it is fully charged by glancing at it while plugged in. Every phone I have ever had before has had one.

So far the Galaxy S II is living up to its promise as a top of the range Android powerhouse. We will be spending many happy hours together..