Actually, I have that 25 in 1 pad and it's not good. It's actually downsized NES (or SNES - I can't quite remember) hardware inside, running an emulator and lots of the games are just wrong - for example, there are far fewer aliens onscreen in Space Armada.
However, the PlayStation 2 collection they just released, called Intellivision Lives!, rocks. The games are emulated flawlessly, you can play the sports games single player now, and there's a metric ton of extra art, interviews with the programmers, and other geeky, museum stuff. And I think it's only about $20. And it's coming to Xbox sometime soon. Can't recommend that one enough.
-Eric