When Impulse first began, it was buggy. It got fixed and I used it to download the updates to the GalCiv series as well as purchasing the expansion packs, but later it seemed to me that Stardock were going to become Game-resellers rather than developers. When it went to Gamestop, everything was fine for a while and I did buy a couple of games through them; then I just stopped using it. There were never any other issues with these applications for me.
Yesterday my zone-alarm found Steam to have a Trojan, which I had to remove via a reboot. Not very endearing to say the least. I just hope that Steam is not as invasive as E.A.'s DRM was with the disappointing "Spore". That has led me to Boycott anything since from E.A. no matter how potentially tempting any title seems.