This was my first pair of Merrell shoes, so I have no history to base the quality of other shoes from this manufacturer. They are comfortable shoes, although they offer different support than that of running shoes (obviously since they are cross-training shoes). Being that I was used to the support and fit of running shoes, it took a little getting used to. I would recommend trying them on before purchasing so you know you like the fit.
My biggest concern with these shoes is that for the TWO pairs that I have wore, the socket in which the lace is inserted (at the top of the shoe) ripped out when I was tying it. This occurred when tugging the laces to tighten the fit- and I'm not that agressive when it comes to tying shoes, so I don't feel I used excessive force. The first time it happened, I thought it was just a freak occurence so I exchanged them for a second pair at REI. The second time it happened, I took a closer look at the stitching- only to see that there is hardly any holding the plastic socket to the shoe. I then took the shoes to a repair shop, they validated my observation that there are hardly any thread bearings holding the socket to the shoe.
Bottom-line, if you like Merrell shoes, you'll probably like the fit of these shoes. However, being new to the manufacturer, I was disappointed with the quality (especially for the price). I've had less-expensive shoes that have held up better.

I don't know why reviewers here stated that Siren is true to size. I happened to be a 7 medium except in running shoes when my feet need room to expand during long runs.
I just bought my usual Asics GT-2140 and Siren at the same time. Asics' 7.5 outsole is longer than Siren's outsole by about an inch!
If you are a true size 7 like me (7.5 too loose and 6.5 too tight), buy half a size up in this style.
The above being said, Siren is cute! I don't need them because I usually wear my running shoes if I must pound the pavement (rare because I live in Los Angeles). However, I just could not pass them by without taking them home. ;)
The outsoles are hard, wieght is light, and top is breathable therefore they should be comfortable in action.
The only thing is that there's very little arch support. If you must have it, replace the factory insoles with your own supportive ones.

Nice Looking, Sporty shoe which fits true to size and width. Comfort wise it's okay but not enough cushion for me. I had to purchase a separate insole otherwise my feet hurt in these shoes.
I'll probably go back to my running Nike's after these wear out.