I thought I'd add an opinion/point of view to the discussion.
Yes or No? For the people who don't care what i think:
Yes, I'd buy it if I had the money. (Or I could convince my girlfriend into buying it for me... (Poor student, why oh why did I go back to study when I could be earning money?)
Now for the long winded bit:
I've worked out that after paying for one years subscription, enough cars and tracks for 2 rookie series, 2 advanced series, Legends road series, skip barber series, and the mazda series would cost me an extra $25 on top of the subscription, after all the discounts/bonus offers were applied).
I'm really not too interested in the oval series, altough have found the rookie legends great fun. I've never done any real oval simming. So being tight on money,
just 7 series 
would do... (Does papy's Nascar being raced with a keyboard count as an oval sim? (The original that is, I still have the original CD and Manual!) 7 series would probably split your concentration up too much.. well for me anyway!
Now, my first impressions of the game were a little dissapointing. I thought I'd take it easy, getting used to the sim, and set out for a 'Test' run by my lonesome at Lime Rock. It was good. Starting out slowly, the car felt good, the car accelerated, turned and broke well. When I started to push, the car seemed to spin so easily, the back braking lose without warning. My first thoughts, wow this sim is realistic! And I'm just a really shit driver, what am I doing wrong? Haha... So I decided to run some laps online to see how others were running. (Mind you, my only experiences with Lime Rock was a few laps with GP Bikes Demo). So I found out, I was pretty slow, and I wasn't spinning from pushing too hard in the wrong areas.
I kept practising and eventually got a bit faster, but was running around on tender hoofs, because I couldn't quite get the feel of the car/sim. I raced a couple of races, keeping up alot of the time eventually. But it wasn't until the next week at Laguna that I started to get the sim. I like Laguna, a favourite track of mine, so I felt comfortable to push the car. It is here I started to notice the feedback from the sim, as I optomised my braking points, turn-ins and apexes. I could hear the tyres working under brakes, getting close to locking, I could feel the car seem to fight for grip in the corners, and get light as I tried to power out. The wheel would be giving me the feedback of when the rear was about to come out. It just took me a week to notice how the sim talks back to the user.
Once I understood the feedback from the sim, my lap times started dropping heaps, I was more confident to follow someone almost nose to tail for a few laps, trying to find the spot to overtake without worrying about spinning out for no reason taking both our SR's down.
The racing is intense with fellow drivers who want to race clean, fair and fast (Well, as fast as me, which is... well a bit slow!). The tracks are superb, and visual, aural and tactile feedback from the game is quite extrordinary once you get used to it, and I can't ever remember another sim feeling the same.
The only trouble for me is a low income due to study, and the lack of time due to assignments to practice enough to be very competitive (Although the hourly races on any day of the week, and divs/qualifying make up for the last point).
I've written an essay, whoops.
Oh, and funkdancer, when you do a track day, do you actually get to race against another 11 Polo GTI's, with timing, results, statistics? Hehe, lapping on track days is one thing, but the thrill of door to door competition is another... even if it is Virtual doors! Good to hear you're having so much fun with iRacing.
I dare say it's a little less than a WRX though 
and i have seen a few people have a big 
as there just smashed there pride and joy