The only problem I have with this phone is the difficulty in linking contacts - multiple instances of the same contact from different places (Facebook, gmail, phone) should be easier to link than they are.
Apart from that, I love this phone. The camera is really good - the colours are pretty true to life (I took lots of pictures of sunset, which some phones just can't handle) and the front facing camera is 5mp - much more than average.
The phone is nice and slim but actually still quite big with a 4.7" screen. It fits into some of my pockets but pokes out the top of others. it feels less annoying in the pocket than other phones because it is so slim.
The pre-installed apps are pretty much perfect, I hate having too much bloat-ware pre-installed and there isn't too much on this phone which is good. also comes with a fairly good document viewer and editor, if you ever want to use those things on your phone. the WiFi connectivity has been pretty good, and internet speeds are what you would expect over WiFi. 3G speeds are also pretty good, just varies from area to area as with all signal related things. I've not noticed any lag in the phone when running multiple applications, and I really like the function on Jellybean of being able to close any application easily without having to download an additional app like advanced task manager.
My previous phone was an HTC Desire, so I expect all other makers have made leaps and bounds since then too, but I am really very impressed with Huawei. It's been easy to get used to, easy to customise and the hardware seems very good.
Also, this phone comes with a case included in the box - don't bother buying one until you've tried it with this case and see how you like it (I originally ordered one which I sent back because it is EXACTLY the same as the one that comes with the phone).