Here's my Rush Hour. And here's my two cents:
The Rush Hour is a great bike. As you can see, I've replace the handlebars, saddle, brake, cog, lockring, and wheels on my bike. All of those, except for the cog, lockring, and saddle, were due to personal preferences.
Stock, the Rush Hour is everything you really need in a bike. The wheelset is decent, and is built around Dimension hubs, which are pretty solid and are used in a lot of FG wheel builds. I built my rear deep V around one, although it was gold anodized. The cog and lockring are cheap as hell and stripped out my first wheelset, but most off-the-peg track bikes need those parts replaced. It also comes with brakes and levers and Wellgo MTB pedals (which I think most people should use, as opposed to track pedals which are popular). The saddle was awful, full stop. I picked up an Avocet R1 the LBS had laying around for $10. The only thing it didn't come with that I thought was truly necessary were clips and straps, oddly. Out of the box, It'll be a great bike, except for the cog and lockring. Shop around a bit, because most shops were quoting me $600 for one but I got mine for $550.
That said, I got the upgrade bug. It's most satisfying to me to have a bike that I built up and customized myself. After paying $593 (after taxes) and $10 for clips and straps, I proceeded to spend:
$130 - Rim, Hub, spokes, nipples - built my own rear wheel
$100 - Mavic Ksyrium Equipe front wheel
$8 - locking skewers
$20 - Tektro RL726 cross levers
$20 - Nashbar bullhorns
$22 - Cheap, crappy, dimension double straps
$22 - Surly 17t cog
$9 - Shimano Dura Ace lockring
$10 - Avocet R1 Saddle
I refuse to do the math, because I might cry a bit. That doesn't even include shipping. But as you can see, it all adds up. I want to replace the stock crankset because it's a bit ugly (nothing functionally wrong with them), but my funds won't allow me to.
So there's a bunch of info, and here's my opinion: If you plan on owning only one bike, go the with the IRO. In addition to saving you money in the end by just simply buying the parts you want the first time around, IRO's also have wide tire clearance (my Rush Hour can take 28c's max) and fender eyelets (the Rush Hour has none), so you can ride your bike in the rain and snow, as well as have some cyclocross adventures.
However, if you plan on having multiple bikes, go with the Rush Hour! I used the stock wheelset on a $5 27" wheeled frame and put some 45mm cross tires on it for winter use. The rest of the parts also found their way onto my conversion and now it's the perfect winter bike.
Hope that helps. And since you're just getting into fixed, let me give you these tips:
1. Requisite reading: http://www.sheldonbrown.com/fixed/index.html
2. Get clips and straps for your bike! It keeps you tied to the bike, which helps with that whole zen crap (seriously), which is good if you want to learn how to spin properly or find yourself going down a hill at an insane cadence.
3. Keep the front brake. It's where all the stopping power comes from. As cool as your bike may look without it, you won't look so cool after your face goes through a windshield.
4. Get a lockring tool! You can use the rotafix method to put the cog in place, but it is absolutely vital that you have a lockring tool and tighten the lockring properly. I used a screwdriver and hammer for my first two weeks of riding fixed and then my hub stripped out and I had to get a new rear wheel (warrantied by my LBS, thank god).
That's all I can think of. I'm on a ridiculous adderall rush, hence long post. But I swear, most of it's useful information. I'm off to go clean my entire house.