will agree with you, but UE3 gets a bit annoying because until the last version it has been console unfriendly.
UE1; This was unique and incredible back in the day. In fact I preferred Unreal graphics to Quake 2 graphics, because of things like the reflections that displayed in the main screen of the game --the 3D scenery was pretty cool. Unreal was also a good game, featuring alien creatures similar to Halo elites, pacific native odd inhabitants with four arms, birds in the sky.., and some fun weapons.
UE2: I only enjoyed it while playing Unreal Championship on the Xbox. It looked to me as one of the most advanced Xbox 1 games out there, graphically wise.
UE3: After Oblivion, Gears of War was the next game that oozed next gen all over it, looking and running better than a lot of games with worse graphics.
I was amazed by the sheer quality of the graphics back in 2006. Besides that, some stages like the krill's one, was pretty cool. I wondered how they rendered two many birds at the same time without stressing the machine.
Also, the rough and clumsy dialogue of the characters helps with the general appeal of the franchise. I mean that without Marcus & company the game wouldn't be as fun if they changed their approach to something like Fable 3 -gag-worthy game sometimes, btw, I'd give it a 2-.
I love that kind of cultured dialogue, but in F3 everything (is and) sounds so childish and stupid... it's not the same at all. Anyway, what I mean is that Gears have been deservedly successful because of the right use of the engine and a decent story, setting and background.
However, save a few games like Gears, most UE3 games lack the same features compared to other engines and don't run that well on consoles, aside from looking like Gears clones. That's how some people grew tired of the engine, except for those games that really make the most of the engine on consoles.