If you'll be using it mostly for stationary shooting from a rest, the extra weight is a good thing. A few people have shot my Sig 556 and all commented that the recoil was noticeably less than an M4/AR15. It is front heavy as mentioned. I have yet to do any CQB drills with it, when I do I'll see how that weight affects handling for me. I'm sure other out there on the interwebs have already written reviews on how it handles though.
I just got mine recently (after the price dropped a lot
) and have only shot it about enough to familiarize with it. So far though, it seems easier to clean than an AR. There's just a bolt carrier and a bolt, not a bunch of subcomponents of the bolt. The chamber stays pretty clean, most of the gunk ends up on the gas plug, piston, and inside the gas tube. The chamber is a lot easier to clean than an AR's chamber, for me anyway. The gas plug and piston aren't hard to pop out and clean either.
Also, mine doesn't seem to mind the cheap Wolf ammo.
One thing you should be aware of is that mine has a habit of dinging the brass up a bit. If you're reloading 5.56, that might be a huge negative for you. Mine ejects it's brass rather wildly. I've seen it throw casings 4 lanes to the right on a covered rifle range, up into the rafters, 10 to 15 yards downrange, etc. I was spoiled by how nicely my M1A put the brass almost within arms reach of my position. Mine also did not like a bunch of the old aluminum STANAG mags I had laying around. It's been fine with the P-Mags I picked up.
I got mine specifically because it wasn't an AR and I hadn't heard anything bad about Sig. Overall, I like it a lot.