I personnally have one on my Wee.
Goods: Solid steel construction. Pretty well laid out for what you are getting. Stable. adjustable for different bikes. Comes with everything you need (including additional relocatable LED brake lite to wire in (your stock one is kind of hidden). Lockable forkmount (secure)
Bads: Eliminates trunk capabilities, crosswind sail issues (pass semi's with caution), pricey, the front lip should have been bent up with the same bungie/net mounting holes. You get in a lot of people's pictures that they post online - usually with an "I thought I've seen everything" tag.
Some mods I did on mine after the first couple days: reflective tape everywhere (most people see the moto, but the bike sticking 4 feet out the back - not so much), LED that came with it can be installed with the license plate - I moved it down lower in the fender and permanently wired it in (can see it in side view). I welded some nuts on the underside of my racks so I can unscrew the rack with 4 screws and put on trunk rack with same hardware.
As far as "loading" and weight distribution issues:
1) It will DEFINITELY create a "tail wagging" affect if you do not put on the load distributing strap (goes from rear pegs, wrap over bike stem, and back down.). Cinched down - it shifts the entire CG of the bike to the fron forks (if I forget to secure the cranks down at the middle, the rear wheel will raise up and the bike will levitate and rotate around the front axle).
2) MTB weighs close to 30lbs, plus rack - and with CG shifted as above - it would be worse to haul around another human on the rear seat ~ 8" further forward!.
3) Crosswinds suck - no way around that. Pass semi's with conviction.
Let me know if there is anything else you were wondering.