When notation software first came on the scene in the 1980s, I was a student at New England Conservatory, and an early adopter of Finale. In those days, I got push-back from some of my professors, though, who were wary that the tool would drive the art too much. Also, seeing my assignments in print, looking frankly more professional than their own handwritten music, gave my work a sense of being completed and some of those old-school professors a reluctance to make changes.

Things have changed a bit, and now it’s much more common to see computer-generated notation in the wild. In many academic and professional circles, it is expected that notation be provided in an electronic format. Finale is to handwritten scores as Microsoft Word is to handwritten text.

Here are some of the many benefits to using software for notation.

1. Legibility. Simply put, computer-generated scores are (or should be) easier to read than handwritten scores. A novice can create publication-ready notation with a computer. Getting a legible hand takes a lot more practice.  
2. Editability. Digital files are far easier to revise than handwritten scores. Imagine an orchestral score, 300 measures long. What if you want to add a few measures into the beginning? It could take many hours to recover from that decision, in a handwritten score. If it was in pen, it could take weeks. But with a digital file, it only takes  a few mouse clicks.  It’s so difficult by hand that you might not improve the score. Not an issue, with notation files.

1. Speed of Note Entry. You can cut and paste repeated notation in a digital score, and this can be a very dramatic time saver. Not possible with handwritten music. 
2. Transposition. To change the key of a handwritten score or part, you have to rewrite the whole thing. In a digital file, again, it’s just a few mouse clicks. You could print a concert and transposed score with a single command, in the digital world.
3. Part generation. Copying parts by hand for individual musicians takes hours, or weeks. Again, like transposition, in the software world, it requires a couple mouse clicks. (And maybe some cleaning up, but it’s still dramatically faster than by hand.)
4. Backup. If you lose a handwritten score, it’s gone forever. Computer files can be backed up, though. If you lose a printout, you can simply print it again.
5. Transportability. Digital files are easily emailed. You can generate a PDF and send it to someone who doesn’t have your software. You can  export notation as JPG or other graphical format files and import them into Word, InDesign, Facebook, your blog, or whatever. Handwritten files need to be scanned first.
6. Layout flexibility. In a digital file, you can change your mind about the page layout for the whole score, perhaps printing it on larger paper or with smaller margins. It’s easy to make grandiose changes like this. But with handwritten scores, the whole thing has to be redone from scratch.
7. Playback. You can immediately listen back to a note-perfect performance of your notation generated scores. You can even export them as audio or MIDI files and use them in your DAW, or on iTunes, or other tools. Try that with your pen and paper.

The two most common notation software products on the market now are Finale and Sibelius; they are roughly of equivalent power. Finale’s street reputation is that it permits greater control, but is more difficult to learn at first. Sibelius’s reputation is that it is easier to get started using, but it is not quite as flexible. Professionals use both, and it is possible to swap files between the two platforms. In my opinion, most serious musicians should get the full versions, not their various derivative products. While I’m personally partial to Finale, and have taught an online Finale course via Berklee for many years, you should probably just use what your friends use, so that you can ask them for advice.