Well, some problems that I've seen relate to resistance in certain circuits, and component failures. For example, in order for the remote start to work, a great portion of the ignition lock circuitry has to be bypassed, to allow it to start without the chip recognition from the key (as I mentioned before), plus rerouting all of the wiring from the ignition switch through other power connections. I mean, it can be problem free and probably is in very many cases, but from all of the experiences I've ever seen for remote start, I'd never install it in my car.
Tell you a short and true story of what can happen when a remote start is COMPLETELY botched on install (bear in mind this was a one in a million, but I saw it happen). We had a car come in with an intermittent start problem on a Jaguar XJS 6 cylinder with remote start installed. It was running, and the service writer pulled it up by the glass windows seperating the service department from the shop, and shut it off while the car was in gear. One of the other writers walked over to the car to move it out of the way (he had just walked through the customer waiting area and his shoes were statically charged from the dry heat). He touched the door handle, and got static shock. Because the car's remote start was wired through the security system, the static shock somehow tripped the remote start, and sent this Jag into a wall right in front of the service desk with the advisor desperately attempting to gain control!
Bear in mind that as I said that this is at least a one in a MILLION chance of this occurring, but it is a good lesson of getting a quality place to install a remote start system in a car. All I will say is to be sure of the work you're getting before you get it done.