Its great for your arms as you are always holding your guard up with gloves on and if your using all the punch techniques you really improve on your back, shoulder, neck and arm muscles.
What you get out of it will really depend on your club and how they train/teach and how much you put in.
Some like to work hard on cardio; running around, skipping, shuttle runs (we do the bleep test), and rapid punches to pads over 5x3 minute rounds (killer).
Boxing is also brilliant for building up robustness and the mentality to deal with discomfort and pain.
Its good to get used to being repeatedly punched in the head, ribs and stomach so when you hit RT and your body starts to take a pounding it wont affect you too much. If you flinch with pain you're not paying attention!
Theres no harm in going a couple times and seing what you get out of it.....
I've been doing martial arts pretty much all my life but to be honest I've only been 'Boxing' for a couple of months.
As for sparring, again it depends on the club and also your confidence and ability.
My club throws you right into it if you want to, as long as you have a mouth guard they'll let you spar.
We do general fitness and technique on Fridays and Sparring on Sat.
i've been boxing for about 5 years now, it's great for your fitness believe me. I've stopped going to my gym now which isn't a great idea because I started my application after i stopped, my trainer was being a bit of a *text deleted** so thats why i stopped going, going to start another gym soon though. I never noticed it was this good with my fitness until i stopped *text deleted*.
Well basically i didn't do any training for a few weeks after i stopped boxing and then started my application and could still do 70-80 press ups in 2 minutes, 110 sit-ups in 2 minutes and 3 miler in just over 20 minutes, so all i can say is imagine what the fitness of me doing them was before i stopped training.
I say get yourself down to the boxing gym atleast 3 times a week for about an hour and half a day. It will help dremasticly! Good luck to you all !!