there will be a challenge low level = low hit points = death from critical hits quite easily. Melee party may have an advantage ...ive never played 5e so im looking forward to experimentation or using these sub classes. I hope all play styles are rewarded
In pen and paper, encounters go best with good scouting, a good plan, and coordinated implementation. Further more, the DM will try to challenge the party, knowing full well if you are a one trick pony.
Personally I like versatile builds that can handle a variety of challenges. If the fighter doesn't have to constantly swap out his weapons for an arcane focus, then the Eldritch knight will be a great "Grover build".
Yes the guy from Sesame Street. He is capable both near and far, and so can the EK be, by using cantrip fire until he gets into melee range.