A bunch of harpies who are angry at reduced profits due to difficulty increases have taken it upon themselves to whine loudly on the forum about how mining is a bad investment.
These people invariably have their own mining rigs: they don't follow their own advice. They're trying to avoid further difficulty increases, which may make them lose money.
Mining is still very profitable, and if it wasn't, these assholes wouldn't be spending their free time trying to convince you not to do it.
In conclusion, if you think it would be fun to participate, go for it. Hopefully you know something about hardware, software, and trading. You'll probably make your money back no problem. It may take a few months. Bitcoins probably aren't going anywhere though.
Just remember: all of these people trying to convince you not to do it, are themselves not following their own advice. If they did follow their own advice, they would sell their bitcoin machines RIGHT NOW to other miners via craigslist.
I'm not selling my mining rigs, and they aren't either, because we all know that mining is profitable and fun and will most likely remain profitable.