Yes, good recruiters can be extremely helpful. Bad recruiters are useless.
Good recruiters will ask you about your skills, experience, and what you are looking for in a company (size, culture, work content, etc). They will then match you to appropriate positions.
Bad recruiters will try to fill positions as quickly as possible, even if it's a poor match.
I've been a software developer for 20 years and have used third party recruiters to get most of my jobs.
Here are the benefits to using a recruiter:
Recruiters will do the leg work for you
They will find positions that match what you are looking for. You don't waste your time applying for jobs that you are not qualified for or are not a good match.
Recruiters usually have a working relationship with the hiring manager
This has a lot of benefits. They can give you tips on what to expect in the interview, how to dress, etc. You will generally get better feedback post-interview; hiring managers are typically more comfortable giving honest feedback to a third party rather than directly to the candidate.
The recruiter will also keep you up to date during the application/interview/hiring process. When dealing directly with companies, it's very common to hear nothing and be left wondering what your status is with them.
Recruiters know the salary range and current market
When companies enlist a recruiter, they give the salary range to them. Recruiters are also familiar with the current market and know what your skills/experience can command. This means you're not flying blind when it comes to negotiations.
I once got a much bigger salary offer than I expected because the recruiter knew the current market and I did not.
Some companies hire exclusively through third party recruiters
There are companies out there that don't want to deal with sifting through hundreds or thousands of resumes and will only hire through a third party recruiter. If you don't use recruiters, you will never see these job openings.