Sport,
I haven't had any dealings with e-surance but I have had experiences with quite a few of the other internet based auto insurance companies. What I often see is that people leave my agency for a cheaper premium and then have a problem or question and have a hard time getting a hold of anyone. Long hold times, slow claim service, etc. These people usually return to my agency within a year. What you should ask yourself is what is most important to you, A) getting the lowest premium or B) having an agent you can go set with face to face and visit when you have a question or problem while paying a fair premium.
you will most likely pay a higher premium with an agent, but with the agent you get service; our face and reputation is on the line with every client that comes into our office, with an agent you get someone who can call the claims office or billing department when you have a problem and get you an answer so you don't set on hold and take time out of your day to worry about this stuff. With the internet company when you have a problem you are on your own and you can only go off of what someone in a call center is telling you, and hope they pass the word along to the right person.
I don't know if this helps, but I hope it gives you some direction in knowing what to expect.