Hello,
I am an overweight male - about 170cm and 117kgs.
A friend of mine suggested a 4 day split weights program that seems reasonable so I thought I would get some opinions:

Day 1: Chest, shoulders, triceps + cardio
Day 2: Lower back, biceps + cardio
Day 3: Cardio + upper back, legs
Day 4: Abs + cardio

I will probably do 4-5 days a week at the gym, so each muscle group will be worked about once a week.

Any suggestions would be greatly appreciated.

Not enough frequency IMO.

Splits are talked about ad nauseam around here. You might want to try a search.

Ok, Im a little confused.
I've been doing a 3 day split program for just under 2 weeks with cardio in every session and I've GAINED about 1.5kg but have dropped a pants size.
Does this mean that I'm putting on more muscle than I am losing fat?
Is this a good or bad thing?

Nobody is going to be able to tell you what's happening in 2 weeks time.

Ok thanks Steve. I guess I need to try and stop being impatient.

I am also confused about full body workouts vs split programs, I've tried searching but just keep reading conflicting opinions.
Im under the impression that you can't lose fat and gain significant muscle simultaneously, so not sure if FBW or split weights program is the way to go for a primary goal of fat loss.
Any comments?

For most, weight training serves as the primary muscle maintainer while dieting. So how you structure it can vary as long as a few key principles are applied.

One of them being frequency.

You can do a split of full body routine while apply adequate frequency.

Your split above does not accomplish this.

A split that would *could* look something like this:

Day 1: Upper - heavy horizontal, light vertical
Day 2: Lower - quad dominant
Day 3: Upper - heavy vertical, light horizontal
Day 4: Lower - glute/hip/ham dominant