The little wall on the left looks like its on an angle from the wall...it should be 90° off of the wall...unless its my eyes? I would start the door with a simple cube, 4 divisions and shape it that way...the top of the door wont be a perfect point. You appear to have started on the blocks around the archway?? and look to be trying to chisel the deformations out to match a real block...if you have...dont. Just block out basic shapes and get the shape right first...ie like building lego.
I would think texture wise this isnt hard but certainly not easy...I think a displacement map would be the way to go so you can utilise the bricks odd shapes to give you real depth when you light the scene...anyone else think the same?
Get the basics right first and then you can build on that.
cheers bullet
bullet1968
"A Darkness at Sethanon", a book I aspire to model some of the charcters and scenes