This isn't the only budget Android phone in town, but it is the cheapest. Android 2.1 for under £100 is a real watershed that should see many other devices follow suit. In terms of competitors, it looks to undercut the likes of the HTC Wildfire, which is a scaled down version of the HTC Desire, available at about half of the price at £200.
It's not in a position to compete on any real level, so if you have the money to spare then this should be your option. It has Sense UI and a much better build and screen quality.
Mid-range devices like the Motorola Dext present a more realistic target, but it doesn't quite have the power and flexibility to compete there either.
This phone goes directly against the T-Mobile Pulse Mini and the Vodafone 845, and it does well against both. Granted both of those devices do slightly more with the Android OS, but the Racer is a well-designed phone with a more attractive price point.
The screen is better than on the 845, and it seems to have a little more grunt despite the identical processing power and RAM. The camera is nothing to shout about with any of them and here it performs worst, while the Music app produces some surprisingly good sounds.
If our money was going on any of the three, then we'd opt for the ZTE Racer.