#1
Line 6 JM4 Looper: http://www.guitarampkeyboard.com/en/76296

I've watched a few youtube vids and some make it look pretty cool, but there's one that didn't really give a off a great vibe about it.

This one: http://www.youtube.com/watch?v=ba5cZo--Muw

I've been thinking about getting it this Christmas. What makes me want it is just that it looks fun and it has a load of stuff I'd use on it, especially the Jam tracks and the looper.
I'd only be using it in my room, I wouldn't be using it live, not for now anyway.
I'd use it for amateur recording purposes, composing and jamming. I wanna use the looper for some cool harmony stuff too.
So it looks good to me!

But I aint no expert! What are your pros and cons, and what do you think is most important to consider?
#2
I kind of agree with the video, if it's a looper you want go for the Boss Jam Looper. If you're into those extra functions go for the spider jam, I tried both and the Spider was kind of faster in processing, plus the sounds are fine tuned for that speaker and will sound at their best.
Guitars:

Ibanez SZ320
Ibanez RG450
Ibanez SC620
Bc Rich Warlock 7 String
ESP LTD SC-607

FX:

Digitech Whammy 4
Line 6 PodXT Live

Amp:

Line 6 Flextone 2
#3
Yea but I have a good amp already. As far as I know the spider jam is only available as an amp, rather than a pedal.
#4
Then ok go for this one, from what you said you seem interested in the extras it has and those are quite good. If you got a good amp already there is no point in getting the spider
Guitars:

Ibanez SZ320
Ibanez RG450
Ibanez SC620
Bc Rich Warlock 7 String
ESP LTD SC-607

FX:

Digitech Whammy 4
Line 6 PodXT Live

Amp:

Line 6 Flextone 2