I just bought the Aldi wireless one (9th July 2013). I would have to say that it sucks, big-time!
When I got home from work, I removed the computer from its clip and it still kept registering, but showing really ridiculous, random speeds, such as 36.7mph, 48.3mph, changhing every second. Eventually, after a few minutes, it shut down. About 2 hours later, I switched it on again and it was still registering silly speeds and it had clocked up a couple of hundred miles while I was having my dinner. I took the battery out, cleaned it, replaced and after going through the setup routine, it started displaying random speeds again. Resetting it doesn't help. There's just no way to stop the damn thing.
I should have known better. I've had other cheap electronic devices from Aldi before and they've been a let-down. For example, I bought a "radio controlled" clock that picks up a radio time signal from an atomic clock. Stupidly, in the UK they were selling ones that were tuned to the clock in Germany - not the one in Rugby, and it's never managed to pick up the signal from the German clock.
Don't buy the wireless cycle computer. Save up a few extra pounds and get a decent one.
(I have nothing against Aldi in general - just their electronic products)