Recommendation: What to say that hasn't already been said. These are amazing. They work as they should...the adjustments are great...they handle the mud well. If you can afford to get the XTR, by all means do it as they just do everything better and at less weight. But, for 99% of us, this is the alpha dog here. Currently (end of 2014), the pricing is around $75 most places online. That's an absolute steal.
Pros: Durable. SPD. Easy to maintain. Easy to adjust.
Cons: Heavy compared to other brands.
Recommendation: I've been an SPD rider for the better part of 10 years. I decided instead of using non-series pedals i would give these a chance since they were on sale. In terms of build quality they are pretty much the same as the PD-M540 with less weight. The internals appear to be the same. My recommendation is to check for axle play after your first ride, these don't appear to be set well from the factory.