The Mercury is almost an excellent tent. Just a few changes to the design and it would be. But as it is it’s only suitable for fairly sheltered sites as it’s not very stable in strong winds. It’s almost a square in shape and easy and quick to pitch. The weight is quite high but it is very roomy for two people with good headroom in the centre and a big porch. It comes with a centre pole though weight can be saved by replacing this with a trekking pole. Two trekking poles can also be used to hold up the main door, creating a protected entrance that only needs to be closed in the worst weather. The sides of this door can be unzipped in good weather. This unusual door is excellent and one of the best features of the tent.
Short poles at the corners raise the fabric so there’s reasonable headroom here, unlike with some pyramid designs. These little poles have pegging points at their base but none at the top, which means that while they increase headroom they do little for stability. They’re also not attached along their whole length to the tent. I think if they had guylines running from their tops and were more firmly attached to the tent stability would be greatly increased.
Robens describe the Mercury as a three-season tent and I would agree. It’s certainly not suitable for winter use or snow and at any time of year I would look for a sheltered site. Robens also describes it as ultralight, which I think is stretching that description.