It is 'ok' for the most part. Allow me to explain my experience.
I was downloading Dead Space 2, and it reported the file to be 16GB.
Due to me sharing my internet connection I can't continuously download, I do it in incremements. The software has a download pause feature which at first I thought was quite good.
I got 50% of the way through the download, hit pause and went to continue it later, once I hit continue it reported the download to be only 25% complete.
Which would be about 4GB, and I checked the download destination and it indeed contained 8GB which is the 50% it reported earlier. I hit pause again, and continued the download once more and it reported it to be only 10% complete this time!
After that I just deleted the 8GB I had previously downloaded and just downloaded the file in one chunk to ensure it wasn't corrupted. In the end it was only 9GB in size too, even though it stated it was meant to be 16GB.
I'm not sure if that was a one off, but I haven't experienced any more problems like that since.
So other than that small issue I have had no problems. I also back up the games on my external HDD and even when you re-install Windows the games don't need re-downloading, simply pull them off your back up HDD and they are good to go. I didn't even need to re-install Dead Space 2, it ran straight off the external HDD with no installation required.
It's nearly up there with Steam in simplicity. I definitely don't think you should avoid the software.