Remington 1100's are nice. I bought one used, and it's served me well the last three years. I have 22" and 30" barrels for it, the first for skeet, the latter for Trap. I'm no expert trap shooter though, so I can't really comment on the pattern/results.
A few things to consider though: if you buy NEW Remington, I'd personally avoid the "entry level" shotguns...quality control seems to be lacking in Remington in recent years. But a nicer/higher end 1100 even today should have no quality problems.
If you buy used, as I did, even if it looks very nice, you will want to buy some replacement parts, such as a new extractor, new recoil spring, new magazine spring...because these get weak and require replacement before they break. Also you'll need to get replacement O-rings, for the gas system...they are very cheap and last for
Rem1100's are heavier than some of the newer semi-autos. They WILL last a very long time...not unusual for a maintained (through spring replacements and proper lube/cleaning) to run well past 300,000 shells. This is a really good owners manual written by a heavy user (not the company), that laid out all sorts of things to look for...The Remington Society's excellent and free booklet on the workings of the 1100:
http://www.remingtonsociety.com/images/Rem_1100_Notes__Rev_with_Pix_of_Disassembly.pdf
Now...all that said, they do have a few disadvantages over the newer “upstarts”!
First is that they seem heavier and are much more “nose heavy” than other newer semis, and seem to get dirtier much quicker than the new designs (I'm used to cleaning M-14's, FAL's, C6's and VZ-58's, so this isn't a factor for me, but it might be a pain in the butt for you). Also, the newer semis from Beretta, Beneli and Browning seem to have significantly reduced/cushioned the recoil. One Browning I tried was...darn near recoilless! Well, with trap loads. And the Benelli Super Black Eagle absorbed a 3” magnum slug so well I was surprised beyond belief. Still a healthy shove, but nothing to worry about, no pain at all. A Rem1100 is closer to that of a normal pump gun, regardless of the shell type.
Pacobillie is correct that if you pick an 1100, about you needing to decide if you are going to shoot light/medium target loads, or heavy hunting/magnum loads...as good as the 1100 is, it doesn't meter the gas between light and heavy, unlike most of the new designs. If you pick a light 1100 for trap, like I do, you don't want to run more than a box of magnums through it in a year...you could break things quick.
Remington 1100's are great guns, and if you treat them right, they will treat you right for decades of duty. But let's not gloss over the fact that they do need more care and attention than some of the new designs. The upside is that used 1100's aren't very expensive, should be easy to re-sell if you wish, are easy to work on, have a ton of accessories for it (it's the AR-15 of the shotgun world...well, after the 870 it is!) and look a million bucks even with a million miles on the odometer! Actually, a surprising number of 870 accessories also fit the 1100.
But...if you just want to compete, have no time/patience/care to fiddle about with spring replacement and O-rings, and want to run the same gun for hunting with heavy loads...and you have the bucks, you might choose a different shotgun than the 1100.
Oh, one more thing: if I had unlimited funds, played Trap/Skeet twice a month every month, and wanted a dedicated shotgun for that, my choice would be the Beretta 391...something about the way it feels/comes together...it's like the Ferrari of shotguns. If I wanted one for trap/skeet but also blast big magnum loads for hunting, I think I'd go for the Benelli SBE or SBE-2, or whatever newest offering they have (Vinci maybe?!?). And guess what? I wouldn't sell my old used Rem1100, because it still works, is my first shotgun, and still has many years ahead!