Before I bought Ldoc1234's Catrike 700, my only real experience on a trike was 25 miles on a 3 speed Terra Trike Rambler. The rambler was fun, so I knew a faster trike would be really good....but I didn't realize how different a Cat 700 would feel.  
 
I get lots of pedal steer. Even with quiet hands on the controls, at higher cadences and power levels the trike swerves back and forth some. I guess my pedaling is not smooth enough. Seems to get worse if I think about it. I tried counter steering, but that takes a lot of concentration, and leads pretty quickly to what aviation folks call pilot induced oscillation.  
The steering is very responsive.
My fastest descent so far topped out at 30 mph. The trike feels very stable at that speed as long as I'm not making extraneous steering inputs or pedaling. I'll need to work out the pedal steer before I try a powered descent to higher speeds.
Finding the right position for the neck rest is really important to comfort with that 25 degree seat angle. I've made a couple of adjustments, and I think I almost have it dialed in. There are circumstances where you want to lift your head up and get off of the neck rest, and I'm finding that's a whole other set of muscles that need some more development. So far, a 12 mile ride is about as far as I want to go.
This trike has 406 x 23 tires up front, 700c x 23 in the back, all up over 100 psi. By a very large margin, this is the most brutally harsh riding thing I've ever ridden. I think thats mostly due to the high pressure racing tires, and a little bit to there being no seat foam. I didn't realize the trade off "cost" would be that high to get the fastest possible Catrike. On smooth asphalt this trike is a dream, but on rough asphalt or concrete with seams, the vibration makes the rear view mirror almost useless, and makes my forward vision a bit janky if I'm using the neck rest. And it's all just generally uncomfortable in that circumstance.
On the plus side, I think the biomechanics on the trike are near perfect for me. My commuter loaded v2 weighs about the same as the trike, but the trike easily out climbs the v2... I can feel that I'm generating more power.
The business about never having to unclip is pretty fantastic. That thing you do on a bike when you approach an intersection with poor sight lines....where you slow down and slow down trying to get a good look before you commit, and deciding whether or not to unclip as you approach wobbly slowness....it's very relaxing not to deal with that. On a related note, that thing where you have to come to a sudden unexpected stop and you find you're in completely the wrong gear to get going again...yeah, no big deal on a trike!  
So I'm looking forward to getting in another ride on it this next weekend, and getting more accustomed to the Catrike 700 experience.
 
 

They aren't called bone shakers for nothing.   I run my tires at max pressure so it will go faster, yep I'm a glutton for punishment, seriously I love it though.  The pedal steer Initially drove me nuts and after a couple hundred miles it just went away, I believe this occured because my pedal stroke improved dramatically.  I noticed the improved pedal stroke on my bike as well, so it was a very good thing overall as my efficiency was greatly improved.  Last week I sat on a road with a Krispy Steve neck rest on it and oh my it was nice, seriously considering adding one to my 700.