This topic has been covered on numerous other threads. Try searching slide out using the search function above.
Some folks really like them and some don't. There have been some reported problems, but the newer ones seem to work fine. We have a 2005 28' slide (no longer made) and after 2 years have had no problems or leaks. The AS slides are built much more solid than the SOB's I have seen. We really like the additional floorspace it provides. Keep in mind the slide out adds a lot to the tongue weight so you may need a beefier tow vehicle.
"THE OLDER I GET, THE BETTER I WAS"