I've heard nothing but BAD things about this half marathon. Whenever someone talks about this half they have like a half-smirk on their face like they know some devilish secret about it. And look at the description of it on it's own website:
Riley's Rumble is the evil half that your mother warned you about. Don't be seduced by the lush bucolic countryside of rural Montgomery County. This race will challenge the best runners. If you want the 3 H's (hills, heat, and humidity), this is the race for you. It is a good workout if you're preparing for a fall marathon but Riley's may not be advisable for your first half marathon. As an alternative, consider volunteering for Riley's and then running Parks Half Marathon (our 'better half') which takes place in early autumn when temps are usually significantly cooler.
The part about it being the EVIL HALF literally made me laugh. I've heard that this race is HOT and HILLY. I also keep hearing the Baltimore Marathon is quite hilly so this race would be good practice for me.