I have a small Garmin GPS I keep in my pocket. Pretty accurate. Use it most of the time. One of the courses I play goes cart path only when it is too wet, so I grab a few clubs and use the GPS when I get to my ball.
I also have an old Bushnell range finder for when I want precise distance to a certain target. Also comes in handy sometimes when I look for my ball, as it also has a bit of magnification. I'm at an advanced age and the eyes just aren't that sharp anymore, so when I hit a long shot and know the general direction, I can use it to locate where I'm headed. Don't think it was intended for that but it beats mounting a rifle scope to my driver.

Nothing wrong with using your phone as a GPS tracker. Some people find that the battery live is a problem and that some apps are not very accurate. Advantage of a rangefinder is accuracy and ability to scope bunkers, water, etc. very quickly. Disadvantage is you have to be able to see where you want to land. Hilly courses with a lot of blind shots are not good for a rangefinder. GPS has disadvantages too. Some courses are not loaded or they have been remodeled and data can be unavailable or inaccurate. You usually get front, middle, back of green distances so knowing yardage to the pin can still be a guess. I carry both a small GPS that stays on during the round and a rangefinder that I use on Par 3 holes to get accurate pin distances. If my GPS is not working, I have the rangefinder as a back up. Pick what works for you. If that's your phone, no problem. Wishing you many more enjoyable years of golf.

Most distance apps give yardage to the front, middle and back of the green. A range finder will give you exact yardage to the pin. Some range finders have slope function, and this will give you an adjusted yardage based on uphill or downhill. Usually, that function is not allowed for tournament play.

Accurate measurements are key, a good rangefinder gives your this and better view into green.. Bushnell and Leupold are tops in the game.

Rangefinders give you distance to the target. I find them helpful, especially my Bushnell ProXE. Get good battery life.

I use a rangefinder in tandem with a GPS watch. I play better golf as a result and here's why; let's say I have a rangefinder and shoot a pin at 160 yards. I reference my GPS watch because I will pull a different club or play a different shot if the back of the green is 165 and the front is 145 as compared to the front being 154 and the back being 175. I know where I can miss, where the pin is located, and where I have room to work. I highly recommend a rangefinder. Bushnell's are usually a good bet. Reliable, accurate, and comfortable to hold. One tip I will give is is you get one you a magnet on it and put it on the cart during the round, take the case off your bag and put it in the front compartment of the cart that way when the round is over and you clean out the cart you see the case and don't leave the rangefinder on the cart!

I use a Bushnell range finder and Arccos. Arccos keeps track of all of your shots and creates a list of stats for all of your clubs as well as your score, then creates a profile you can track and rely on. Arccos also gives you a map of each hole with an excellent view and the ability to measure distances to water, bunker and hazards.

i use both on the course. the gps is great to see if a hazard is hiding from you or what your landing area looks like. i use my range finder for par 3s, approach shots. when i play in tournaments its the best way to chart your course.

The GHIN GPS map works great as well, shows a green view, with undulation arrows. Around Florida where I play in these cookie-cutter developments, they use retention ponds for re-claimed water everywhere, its helps to have an overhead type map on your phone. Problem with GHIN is it's always reading, so your phone will have a hard time with 18 holes.

I never trust the GPS, been shafted too many times.
Approach shot is always calculated with a rangefinder.

as a beginner no, as you begin to get consistent with your clubs and have an accurate understanding of distances with each club it will be more useful

I have previously used a rangefinder and currently use a GPS. There are advantages and disadvantages to both. I like my GPS but may go back to a rangefinder. I miss being able to target distances for bunkers, water, trees etc. My GPS (Phantom 2 from Bushnell) is basic. I find it just takes more time to toggle through for target distances versus just shooting them with a rangefinder.

Matthew - I think most have found that having both a GPS and range finder help us navigate the course. You will use both in specific circumstances and then there are times when you can use either. I have found that Bushnell makes a great product. I have the new ProX3+ (warrantied my ProX3 and they sent me the latest model) and I pair it with the GPS app that gives me all the information/stats I need for a round of golf. I can't recommend Bushnell enough. If you're in the market give them a look.