The Strava app, as with most 'apps' I know of are purley limited to the GPS powers on the phone, not the app itself, so GPS performance may vary. some Phones are not as good as others. Having a data connection on or wifi at the start should speed up initial gps lock on as it is assisted, possibly even get current sat locations.
Of road of course has the large problem of trees, you etc in the way. IT needs line of sight to work properly.
I got my dads old Orange SanFrancisco (ZTE Blade) phone off him as he cracked the screen. For me not a problem I just wanted it to log rides.
I have used it in my pocket, thrown in my back pack etc. BUT the best and most consistent way is at the top of my rucksack, in the top most pocket. I don't get in the way at all then.
There are apps available for heartrate, and all the other monitors, (strava can do this too) even barometer if your phone has it. Other apps may also do this and when platforms evolve and apps evolve. Which is the one advantage of Apps on Phones or similar devices, easy to try and easy to add features.
The phone does all it's data transfer too. You don't in fact need a SIM card or mobile operator as you can use Wi-Fi when you find a connection. (at least on my phone).
for people that don't do phones
, don't think of them as phones. They are mini-computers with a lot of data-logging sensors connected. Once you understand that, it's much easier. Some just happen to have the a phone 'sensor' added so they can be used as a phone.
I like Strava because I like the segments. Only my 'friends' can see my logs as that what I have my settings set to, so I don't need to make private all the time.
Why do I like the segments, it is interesting seeing that I was quicker up the radio mast this year (the peaks national just gone) than last even though I didn't feel I was*. I can compare my times over that segment very easily. Being a long segment (time wise) it's going to be pretty accurate.
Short segment not though due to the very crude way Strava works and calculates things and the inherent inaccuracies of GPS. There is no point going fast than something if it's only a 3 second change you're looking at. It is not that accurate. Strava tells you themselves how 'poor' it is, read what they say.
While I use 1 second intervals, the default for Android is 3 second and then due to the way Strava calculates after uploading, for a segment, you may be 2 or 3 secs better or worse than you are if you happen to have you gps location correct.
That is where segments work though, compare to yourself and your friend over time.
(or for knackering out the new riders you made use it and keep telling them 'this is a segment' and watch them bomb off
*and some bugger called Martin was 3mins 30secs faster (I was just of 16 mins) on a 1989 MS Racing bike... and I was one of the 'quick, actually road all of it' ones, lol.