I will admit they could have done better with the army voices, the 'Ow he got me' was especially cheesy, but bearable. The scientists voices didn't all completely sound the same, especially when they added female scientists to the mix. Scientists sounding the same didn't help much, but it didn't hurt it in my opinion.
I will admit that sometimes I would get lost because of the maze like laboratory, but I found that locked doors looked the same, so I knew that they were locked without having to go check most of the time. Also about the buttons that need to be pressed were always glowing, so I didn't have to waste time figuring out which button to press. I also found that I could go back and talk to the scientist that told me what to do earlier and he would tell me my progress or what I should be doing, which always helps.
Oh, boo hoo. You sound like one of those COD fags who complain about other FPS games when their health doesn't regenerate. The shotgun takes care of them with one shot easily. I rarely got hit by them because I would kill them before they could even manage to do their attack. Also, a grenade took care of most of them in that small room with a bunch of them.
Again, you sound like you are whining. I'm happy that they didn't wait for Xen to be completed because I'm sure most people were tired of waiting. And they gave you the long jump module so that it fit with the story. Taking it out just because they weren't finished with Xen would not make any sense.