You will have a program guide, but channel switching isn't exactly instantaneous. I just timed one and it took 5 seconds. Sometimes it takes even longer. This is for a TiVo HD model, with a Tuning Adapter on Time Warner in SW Ohio.
Whether this would be faster without the TA, I don't know. But I would be unable to get half the channels I watch (which are SDV) without it. Also, about 5% of the time (just a guess) tuning fails and has to be retried, or if it's for a recording I just miss the recording. TiVo has been aware of the problem, which can occur on Premiere's also, for well over a year and could fix it quite easily with a software update in my opinion ... but they haven't.
See if your TWC region is using SDV (and thus you need a TA). They have been a real PITA for many folks. Some TiVo owners just don't use the TA (thus giving up channels they should get) just to avoid the hassles.
In case it hasn't hit you yet, the technical and purchasing aspects of TiVo have become much more complicated since you last owned one.