I have both ,the Nexus 4 is the better phone quad core / 2gb ram makes this phone very fast, response and customization is excellent on this phone ,if you have to choose one phone the the Nexus 4 has alot of development going on for it and is a very good andriod phone.
For me the bigger screens coming a pain as they get bigger and bigger 4.7 inches on the Nexus4, I owned the Samsung note before but got tired of lugging it around .
I use the G330 day to day for work as it has dual simm and is only a 4inch screen so is easier to hold unless you have humongous hands.
The G330 is a step up from the G300 had 2 G300's before. The G330's screen definitely looks better then the G300 and being a dual core it is much more responsive.
The G300 was very creaky and felt less robust , the G330 feels alot better made and doesn't creak when you squeeze it phone construction is a step up from the g300 .
Customization for this phone at the moment is asian based as this phone was released in the asian market a few months ago.Saying that the amount of roms for this phone v other chinese phones is greater at the moment, check out romzj.com so the phone has potential.
All of the ROMS I have tried have english so it is a case of using titanium backup to take out unwanted bits. The stock huawei roms are available for china unicom which contain english so you can always go back to stock , but you still need to customise or remove the chinese apps.
I have managed to customise the phone quite a bit (google translate if your friend).