I think that the Ortofon 2m red is an excellent cartridge, depending on what you're looking for.
It's a fairly detailed cartridge for the price, but it's real advantage from my perspective is its high output. If you find your speakers to be underpowered, or would simply like to keep the volume knob turned down a little lower, then the 2m red is a great candidate. I've hypothesized that it might have been designed this way to make smaller hifi systems seem more impressive. I don't mean it as an insult either; it's actually pretty neat!
In short: If you're looking to give your system more kick, it's worth trying. If you're more than satisfied with the power of your system, the recommendations already given in this thread are great options. If you're looking for a warmer sound, Grados are also an interesting choice.