Hi, Jim!
First, (as I ALWAYS suggest) when asking for an opinion about a certain piece of equipment, it is MOST helpful if you provide a Manufacturer name and a Model Number. Reel-to-reel machines were produced at all SORTS of quality levels, from "Washing Machine-sized" professional units (like Ampex machines and others) to portable "tabletop" units that were relatively inexpensive, to simple tape transports that didn't include record or reproduce electronics.
Generally speaking, it is far more common to find a reel-to-reel machine that *does* have record and reproduce electronics included. In this case, the Output would feed into a Line Level Input of your preamplifier (like a Tuner or Auxiliary Input). There *were* several "transport only" decks produced. I recall a BSR deck from 1965 that cost a grand total of $19.95. No electronics were included, but at least it DID have the Record/Playback head and an erase head included at that price. (Hint: It was NOT a "great deck.")
A reel to reel tape unit isn't as "fiddly" or "fussy" as a typical turntable. While it DOES require certain maintenance or setup procedures, once set up properly, it can function quite well with only normal head cleaning for months and months on end. During setup, the tape heads are degaussed, (de-magnetized) cleaned and then aligned to a "standardized" alignment tape. The electronics are calibrated for the proper "standard" reproduce and record levels and the record bias is adjusted for the tape type you have selected as your "normal" recording tape type. (Different types of tape require a different bias setting to produce "flat" recording and reproduction response.)
So how does reel-to-reel recording stack up? Quite fine, thank you. Consider that MOST of the music recorded from around the 1950's until the 1990's was originally recorded on magnetic tape, prior to being "mastered" for vinyl on a cutting lathe. By the same token, reel-to-reel recorders can also be rather abysmal, IF they are compromised by lack of maintenance. It's also safe to say that the final performance will depend TOTALLY upon the quality of the recording itself. If YOU are making the recordings, YOU will control exactly how good the final result will be. If you are depending upon commercially produced tapes, the results can be either VERY good, or BARELY adequate - depending upon the care the duplicator placed in the product being produced.
There is one thing you will notice: Tape hiss. While noise reduction techniques can reduce the overall tape hiss levels, (think dolby-B or dBx noise reduction), most consumer reel-to-reel decks did NOT have these technologies included. In MOST cases, it would require an external unit to encode and decode the audio. Most commercially-produced reel-to-reel tapes did NOT include noise reduction - unlike audio cassettes which usually WERE encoded with dolby-B noise reduction.
I hope this VERY brief "overview" will help you with your question, but PLEASE let us know what make and model of reel-to-reel you are considering.
Sincerely,
Bill Thomas