I know you are asking about the S5 and my dad really likes his. He says the battery life is just ok, but everything else works smooth.
I figure Id talk about my S3 since its pretty similar to the S5.
I have had the S3 for almost 3 years. I like it for what it is, however the battery lasts about 20 hours and I have to charge it every night. I dont like the extra samsung junk that does bog down the phone, I dont use any samsung addon. However it runs pretty smooth. The camera is good on it, nice pictures, it has an HDR, Low light, and Panoramic setting, which I use all of them quite a bit. Its a decent phone for the money, as long as you dont mind the added samsung junk.
If you are looking for a stock android phone, I recommend the Google Nexus 5 or 6. I think this is a more quality phone over the S5 and more phone for the money.