One of my computers is an old Oceanic VT3, which I've read hardware-wise is the same computer. Can't confirm or deny; looks like it, though.
Advantages: works, a battery lasts a lot of dives and is user changeable (though not easy for me; I'm not technically inclined), you can change it, and it can log quite few dives then download to your computer. Decent display. Air-integrated transmitter option.
Disadvantages: doesn't have a color screen like those fancy OLED, but then again, isn't hard to read in sunlight and doesn't plow through batteries fast, either. Interface is not easy & intuitive. I need to review the manual on trips to figure out how to set it to nitrox. And I loathe the manual; it's like instructors for setting a digital watch.
My question to you is, what are you going to do with it? If it's mainly going to be a depth gauge/bottom timer/dive logger/wireless SPG, and the only thing you plan to change frequently is setting the nitrox mix, then sounds like a fine deal and you should be happy.
My other computer is almost the opposite; a 1st generation Atomic Aquatics Cobalt. Console, sweet color screen, intuitive interface, very nice. And I do more with it, without consulting a manual; I don't just set an EAN mix, I set tank size, for example. But it's not on my wrist, and it cost a whole lot more.
As cheap as the DG03 is, let's say you buy it, and 4 years from now decide 'Nah,' you'd rather have something else. You're not out a lot of money to try it, and you can use it as a backup computer.
Richard.