I have one of these chinese phone
It looks like a galaxy 3 I think. It has some good and some not so good features.
Good. Looks lovely, jelly bean OS is fab and very responsive. lots of clever things like the galaxy has (my friend has one). Not quite as tidy as the galaxy, ie messages arent on a nice coloured background, but keep scrolling themselves down, otherwise OK. Internet fine. facebook fine! Camera is OK, obviously not as good quality as a samsung, but perfectly adequate for snaps. Dual sim works well. Battery average, about a day with data, roaming etc, but its got 2 batteries so you could always change in emergency.
cons. gps wont work no matter what app i use. Worse is the coverage for 3 network. My other phone from 3 worked everywhere but they couldnt guarantee the sim in this foreign phone! True! its really dodgy even in my house, generally OK out and about, but a bit anxiety producing. I put an 02 sim in the other dual slot in the hope it would work better, but the bars are not much better and despite topping up £10 as per instructions, 02 say my balance is nil (still working on that). Recent holiday to norfolk resulted in no signal whatsoever, complete radio silence!
My contract is up now and i am going to try with the 02 PAYG for bit to check for coverage using only the 02 network, and if thats not working go for another package deal and sell my phone on ebay! It is a very nice phone, pity about the 3 coverage, which is the only real downside. Worth giving it a go I would say and try out your SIM in the new phone. If you have problems they will probably take it back if you say you have no coverage. Check out all the customer comments on amazon as these are pretty reliable. Basically said what I found 
Word of warning. Before I got this chinese phone i had another one which was no good as only 2G (read the blurb sneeze) so after fiddling i sent it back, but only after resetting 'reset factory settings' NEVER NEVER NEVER do this. It reset to all chinese, and I couldnt read a thing.
Luckily they accepted it back with a full refund, phew! 