I started with an RTR TC4. I found it a bit frustrating as no matter what I adjusted, I could not get the car to inititiate turns well at anything over very moderate speed. Instead, the car would just run very wide in any turn at a decent speed. Others have had this experience as well. As a result, I gave up on the TC4 and gave it to my son for bashing (he is 5 so he isn't all that concerned about precise turn in response yet). However, people may have found a set up that solves this problem by now. Try looking at the TC4 thread to see.
Another consideration is that the electronics included with the RTR TC4 are pretty low end. The steering servo is quite slow and does not always center well. The motor is fragile and tends to break in moderate to severe crashes. The speed control will overheat and shut down if you accelerate and brake hard over a 4 minute run. Also, the speed control does not have a lock-out for reverse, so many tracks won't let you run with it. The radio, while acceptable, cannot be upgraded to Spektrum.
Thus, if you think there is more than a 50% chance that you will want to race, you might want to think about buying low cost but race-ready components and a kit. One choice is to purchase the Team TC4 kit or the HPI Pro 4 kit. I have seen both of these at less than $200. Then purchase low cost, but decent parts like the Futaba 9451 servo (about $80), Monster Stock Pro motor (about ($30), Hi Tech Aggressor SRX radio (about $100), Spektrum module (about $160), and a decent Novak or LRP speed controller (about $80). If you get into racing, you will likely want or need all of this stuff anyway.
On the other hand, if you really are not sure about racing, the RTR TC4 does get you going enough to play around and decide. Just note that if get serious abou racing, you will need to start upgrading all of the above parts. Fortunately, if you get the RTR TC4 for about $220, then you are only spending $35 over the TC4 kit for things you will replace. Note, that the RTR TC4 does have inferior shocks compared to the TC4 kit, so you will want to upgrade these at some point as well and this will cost about $40.
Good luck,
Ira