Generally an unimpressive place to shop. What's most upsetting is the regular failure for sales to be provided; at least 70% of the time I have to ask for clerks to apply a sale that is advertised in the aisles. I shouldn't have to do this work!!
Also, basic staples tend to be slightly more expensive for lower quality products. The bakery is often out of basic products (e.g. baguettes) and they tend to be pricey (upwards to $3/loaf), and sell amongst the most disappointing croissants I've purchases at a supermarket (and I didn't exactly come to the purchase with high expectations in the first place).
The saving grace for Metro is its proximity to a large, mostly captive, series of residential buildings. But other than convenience and relative cleanliness it's hard to imagine what would 'sell' this store to a non-captive shopping audience.