We had 15 various Alside Excaliber (I think this line has been discontinued and replaced by the Mezzo line) 4 years ago in 2010 and have had NO issues since. We had some sliders, a LARGE picture window, regular windows, some with obscured glass...
we've been nothing but happy with them. We are getting ready to have an Alside patio slider door installed (a 6100 or higher) and 2 of the Mezzo sliders to replace basement casement windows. We were looking at Pella, but the reviews of their customer service honestly scared us off. We DID have some minor cosmetic issues right after installation, but the installer (same as we're using now) took care of the issue immediately.
Could be that most problems are caused by the outfit doing the install vs. the product. Since my installer is NOT Alside, they probably stand more on THEIR work and getting it right as they do install other brands.
I guess it's about as broad as it is long, but we've been happy with the windows we have. I'd think if the brand was bad, the installer wouldn't use them.