Do a search on ar15.com in the Armory section, or hkpro.com or hkweaponsystems.com for Vector.
I think in general you will find that there have been some mixed reviews while Vector worked out some of the kinks (especially with the V53 with is a short barrel version of the HK33)... but now most people are very pleased with the V93. Also, Vector has some of the best customer service in the firearms industry. If you do have a problem, it will get fixed... they will make it right.
Me personally, I went the build route. I bought a receiver from Vector, parts kit from DSArms and enough US parts to comply with the law.... and sent it to Mark Galla
www.big50hk.com so he could build it up for me. Then end cost is a little higher, but you get slightly more attention to detail in the build (in other words, it is pretty and functional). But this approach takes about 3-4 months....