Yes, as we'd been anticipating, Mechwarrior Online is now in open beta, which means it can be played for free, without restriction. I've been enjoying it a fair bit in the past couple of weeks, but then I am a sucker for both robots and multiplayer combat, so it could pretty much have been designed with me in mind. I would say that it hasn't exactly held my attention for long periods - unlike Planetside 2, for example - so it's lacking something in the long-term reward sense. It also offers a fascinating contrast with Hawken, the faster-paced, jetpack-heavy robo-deathmatcher that's in closed beta right now (but should soon hit for free).
I've posted one of the community-made trailers below. It's quite good.