You hear mostly only the horror stories. I for one have never had any issues with E*'s customer service. I usually deal directly with Tech Support however even on "service" or programming related questions. The consensus is that TS is a bit more savvy in a lot of matters.
There are many things to "watch out for". You want a competent installation. How can you be sure you get one? The best bet is to ask some pointed questions up front. Confirm that the installer is going to provide the equipment necessary to get the programming you requested. Ask which receiver(s) will be provided. Do they provide the features you're planning to pay for? (Are you getting HD, a DVR, multiple rooms, etc.) If you sense any confusion there, have the installer resolve it with E* before the installation begins. Ask where he plans to install the dish(es) and why? There could be options and you need to resolve that before the installation begins. Do you need any special treatment, like wall fishes or special coax runs, etc. Ask ahead of time. Is there a phone connection readily available? In most cases you will want to connect your receiver to a "land-line". How is the tech planning to ground the system, weather-proof the connections, etc. If he is unable or reluctant to answer these questions then you might be on the cusp of a problem - air it out beforehand. (There is no one right way to weatherproof equipment, but there should be at least some consideration given. Ask him where he will place the "drip loops". Some take shortcuts here and don't do them correctly, or at all. By asking you're placing him on notice that you expect drip loops where they are warranted. He'll be less likely to take shortcuts.) Make sure the installer spends a bit of time optimizing the dish(es) for best signal strength. And finally make sure he spends at least a few minutes showing you how to operate the equipment, how to use the remote(s), etc. If you ask some good questions that show you have at least some knowledge about what constitutes a "good job", then you're more likely to get one! And if you think the installer has indeed done a good job for you, give him a nice tip, $20 or more.
Good luck on your installation. Welcome, BTW...!