Almost any notation program will allow you to "Save As" MIDI, and any program that can save as .mid should be able to open any .mid file and show you, in notation, what notes the file plays.

Since there are a few notation programs, especially in freeware, that don't include the dual midi/notation capability, it's worth looking for one that does.

As mentioned, there often are "compromises" in converting midi note durations to note values in the manuscript version, so some midis will produce horribly messy scores. Sometimes it is easier just to listen to the midi and "write your own" score from what you hear; but often you can use the converted score with a little cleanup.

In notation, one frequently uses repeats, to show that a part is played multiple times, but midi will simply play it multiple times, so a score that fits on one page may convert back from midi as many pages (I've seen 20 pp or more for some simple 16-measure tunes). Figuring out what can be cut out using simple repeats/codas/DS/DC in notation can be tedious, since often a "replayed" phrase actually is different, so you may have to make decisions about which to put in repeats and which go in the DS cycles.

It's also common for those who "compose in midi" to use multiple "voices" to get just the right "flavor" for what might be a single instrument in notation. When you bring a midi into a score, you may find two or three staves, all of which contain parts of the melody, with no single one that contains all of it. This is more common with the midis that "really sound great," and isn't usually a problem for simple stuff used just for trading tunes.

Generally, any notation program that says you can save as midi will be able to "open" a midi and show it in notation. There probably are exceptions, but it would certainly be a "clue" to whether a program you can snatch easily will do what you want.

Given the amount of manipulation and massage required to make clean and useful conversions, you probably will eventually want to get one good program that you can study enough to learn the tricks that make it easiest for you; and spending a nominal amount for one you like is quite worthwhile - for most of us.

John