Is it worth it as I have never played any of them?
Not sure what they are like and such.
Thanks

I never played JA 1 but the second is lovely. If you like turn based games with guns n' grenades instead of magic and arrows then the JA series is for you. Plus, the characters in that game are quite unique. If you like mods, there tons of them for JA2, not sure about mods for JA1, though.

Maybe think about buying JA2 alone then?

I would.

I was mixed on JA2 when I first got it. Mainly because my team of Mercs was obliterated on the first couple of tries in the starter town. The Game is slow and highly involved in tactics (both of which I like).
But for the first few hours, things just did no work and I turned it off.
6 months later, I reinstalled for another try, and after a little bit of fussing around, everything just clicked and I found it has the "Just one more Turn" aspect keeping me up until 3am.
It requires dedication, but if you like the type of game it is, once you learn it, it's easy to get hooked.

is't that kinda like fallout 1 and 2?

I'd say it's more of Fallout: Tactics.

It frequently gets compared to X-COM (a.k.a. UFO: Enemy Unknown)

JA 1 was pretty good, but I never got round to JA 2. I do have a disc for it somewhere.

JA2: It's so damned good that God himself will not permit you to die until you play and complete it.

Agreed. It's huge on tactics, and the RPG elements are mostly included for variety.
There are also some strategic elements about building up and training forces in each area of the game, so in that respect it's a little bit like X-COM (as Mobius mentioned), but not anywhere near as complicated.
If the strategic stuff isn't your kettle of fish, try Unfinished Business - most of the strategic planning was axed in favour of the tactical combat.
My favourite moment in JA2 was finding myself absolutely unable to assault a heavily fortified warehouse in one city... then going to a weapon store, buying an RPG, blowing a hole in the side of the warehouse, and coming at the enemies from behind.
What other game will allow you to do that?