This is a phenomenal race, and very beginner-friendly. The distance is easier than the MCM, the medal is a unique military challenge coin, and the expo has a cool selection of Army equipment and vehicle displays (besides the traditional running expo). And there's nothing quite like thousands of runners and fans together on a beautiful course through the nation's capital!
The experience is especially great for anyone with ties to the Army. The post-race area is full of tents from different units, and you'll almost certainly find yourself running next to colleagues and friends from throughout your time in service.
My only quibble with the experience was the wave starts, while initially well-organized under different banners with colored balloons, slowly merged together into chaos in the later waves. But overall everything was very well organized and thought-out, from the water stops down to the busses from the finish area.

This year's weather definitely made it a wild ride (alternating drizzles and downpours for the first few hours, ankle-deep water in a few parts of the course, and then suddenly 70s and humid when the sun came out), but it was an incredible race overall. This was my first marathon and the MCM is a very beginner-friendly race. The course is pretty flat overall with beautiful scenery through DC. Not to mention it is incredibly energizing to run with a field than big and so much fan support at nearly every mile. The Blue Mile and Marines manning aid stations and handing out the medals at the end make for a meaningful experience. Highly recommend!

(My only reduced stars for parking/access are partially because this race is so big. While the metro opens early to get you there, there's a decent walk to the start line and after the finish line. Can be tricky-ish to meet back up with people.)

This was the first negative experience I've had with a race. Terrain Race advertised free early registration, but piled on the fees and add-ons. (I understand the need for event insurance and venue fees, but be honest with your pricing if those fees are as much as entering a local 5k costs.) Everything seemed more focused on making money than on the race experience. Pre-race emails and packet pick-up *heavily* encouraged runners to buy merchandise. The gouging continued on the day of the race. Parking? Suprise, it's $20, cash only. Bag check? That's another $15.

The course itself was...ok. The raceway setting was kind of neat. Very little mud. Decent mix of obstacles including tough ones, but there was no "punishment" (like burpees) for failing them, nor was there the help-strangers-over-the-wall camaraderie that other obstacle races encourage. The organizers had a difficult time managing the waves, so lines backed up at most of the obstacles. The aid stations (just water) and obstacles were sparsely manned by one or two volunteers; I'm curious and concerned what would have happened if someone got injured.
We weren't even entirely sure we finished until we reached the line for t-shirt pick-up, as there was no real finish line marker or celebration. Swag was a cheap cotton t-shirt and a medal (that I'm honestly a little surprised wasn't plastic given the rest of the experience). Post race-snacks? Nah, but there's a single food truck you can go to.
While the race may be fun for newbies to obstacle racing, the whole thing left a bad taste in my mouth.