Is this an Integral Designs Silshelter and Bug Shelter?

I've used one a little, and found that in spring and fall in Ohio (when there's still a fair amount of humidity, and a 20 or more degree drop in temperatures at night), you'll get condensation on the inside of that particular shelter - and also virtually any other shelter, including my Hubba, if you pitch the fly and don't leave sufficient ventilation.

I found that the condensation was minimized, usually to the vanishing point, if I could leave the vestibule flaps wide open. Like Phat said, ventilation is the key.

However, I found that floorless shelters, pitched on grass, tend to have more condensation issues. (I always leave mine pitched overnight in the yard when I first get them, too.) I believe this has to do with the fact that grass also holds moisture and "breathes" on its own, releasing moisture - thus you have an additional source of moisture underneath the canopy. It's a source that, camped on forest duff, isn't there during actual trips. And, sure enough, in the field, the condensation was much less.

You won't be able to make the condensation go away completely, but don't form an opinion on the shelter until you've had a chance to use it in the field. I always thought the Silshelter was one of the better shaped tarps/single-wall shelters out there. The only reason I quit using it was that the Hubba is simpler, and because, if you need bug protection as opposed to a simple groundcloth, the Silshelter and bivy sack or Bug Liner weighed nearly as much as the Hubba.