According to Wikipedia, CRM is an approach to managing a company's interaction with current and potential customers. For most CRM systems, it typically means acquire potential customers (lead), figure out good candidates (opportunity), actively follow up with them and hopefully work out a business (deal). After that one would also try to keep a long term relationship with them (contact).
However, one must remember that, the CRM is a tool, eventually. And it's the tool that serves you, not the opposite. If the CRM has some features that you don't need, then no need to panic, it's totally fine to leave them there. A lot of times people are overwhelmed and panicked when they start using a CRM and find tons of features there, that's just unnecessary, simply forgot about them if you think you are never going to use them. You would use them when you need them.
Also, one should remember the CRM, despite its name implication, is not restricted to serve 'customers'. The core of CRM is a tool to reduce the pain when handling people related work. So you could actually use it for team collaboration, keep track with your handful of ever lasting customers, and even for your own task management. Working with yourself is often a special kind of people management.
Some people may get used to using pen and paper to take notes, and that's totally fine as well, as far as it works. In fact pen and paper are still most intuitive and efficient way to for note taking in some scenarios.
However, you might try out the new tools when you start feeling that your existing tool set are inadequate, e.g. your notes are easy to get lost, or searching the notes becomes a bigger pain as time goes on.
Some CRMs are as simple as a phone book tool, and some are as complicated as high school mathematics. Naturally, the features of a tool is directly related to the its complexity.
Ideally, one should try to find a tool that is just enough for your use cases, not more and not less. So the core of the problem is, what exactly do you expect from the CRM:
1. do you expect a bunch of reports for administration meetings?
2. do you need the CRM to track down the invoices?
3. do you need the CRM to track down the customer events for prompt response?
4. or you only need a CRM to keep you sane among the enormous communications?
Some enterprise CRM, like Sales Force definitely provide all those features, and much much more, but it's complicated, expensive and need a long learning curve. There are even hundreds of all kinds of tutorials up that.
Some CRM, are as simple as a phone book with additional attributes. But it's also good enough if that's all you need eventually.
There are literally hundreds of CRM products outside. Naturally, there are a bunch of CRM fall into the middle approach, such as Simple Mobile CRM (Mobile CRM).
Simple Mobile CRM briefly integrates basic management for opportunity, note, to-do, teamwork and transcribed call.
The most distinctive feature is that the notes can be shared between Mobile CRM app and Gmail, just install Simple Gmail Notes on Gmail desktop, then the notes can be synchronized with each other.
With the transcribed call, this app allows you to hear the conversation recording and read the corresponding text transcription. They are all automatically generated. In this way, you will not miss any customer details that are mentioned in the calls.