I'm fairly new at modeling and I haven't try all manufacturers but I can see some differences in the quality of each kit. Most modelers can handle these imperfections easily but sometimes it can be frustrating. Here is what I like about kits and what I don't:
I can deal with flashes, pinholes or misalignement of molds but I don't like the lack of details of certain kit. Example: The complete interior of a trailer molded in only one piece (ammo, cans and boxes) !!!! I hate huge surface molded details. Separate pieces please!
What I don't like also is poor engineering; I mean when parts are made in a way that it is very difficult to assemble. (No locating holes for example) I experienced that on my last Italeri kit; the shields of the FLAK gun are held by two pins that has to be glued at a certain angle but there is no guide or instructions about these angles so you have to assemble the shield in place with its two pins all together on the frame, practicly unfeasible. I finally managed to have it done but its all bent and wrongfully located.
But even then, when I look at the final result, I'm proud of what I've done. When I started to build the Italeri Sd. Kfz. 10/4 with FLAK, I was sure it wouldn't be my favorite cause when I opened the box, I noticed the poorly molded parts and thought that the result would be ugly. But when I look at it now, it is my favorite ... for now ... You can see it here http://www.finescale.com/FSM/CS/forums/624710/ShowPost.aspx
So, don't let the bad reputation of a manufacturer ruin your chance of having your favorite model on your shelf.
No matter where you go ....... there you are.