Lord Snooty

I don't know about the difference in temperature but it looks good for the price. At least it'll provide protection from some frost, excess rain and cooling/drying wind.
As it's plastic rather than glass, it'll cut out uv rays so plants are less likely to burn, but ventilation will be more difficult to control compared to a conventional glass greenhouse as the vents are only in the sides rather than in the roof as well. The frame looks as though it might be quite light so you'd have to be careful in high winds unless it's sighted in a sheltered place.