Whether I want specialisations or not is sort of a difficult question, as it feeds into the bigger topic of where Halo is going as a series. Right now there are three main directions it could evolve in, each with quite a few pros and cons; the first, a return to 'classic' arena-style Halo where everyone starts exactly the same; the second, its current form of arena-style with customisable elements; and the last, a class-based system in which players are equipped to fill certain roles. While specialisations would obviously be essential to the third option and completely inappropriate for the first, in the second there's a lot more room for discussion. For the record, it's actually this customisable arena style that I prefer, though I do enjoy the classic style as well.
It goes without saying that any specialisations would need to be balanced, but that alone isn't enough to make including specialisations themselves balanced. For all I really liked the loadout system in Halo 4, one of the things I hated about it was the arbitrary system of unlocks. I've used the Team Fortress analogy to explain this before and I'll use it again: think what it would be like if you could ONLY play as a Heavy or a Demoman in TF2 and you had to unlock the others. It's fantastic if you like playing as one of those, but if you're naturally better with something like the Scout or the Sniper, you're at a huge disadvantage, even though the classes themselves are balanced. It doesn't matter how well balanced your loadout options are, if players can only use certain ones to begin with and then have to unlock the others over time (however small a time), then it unbalances gameplay. While person A might well get something which suits his playstyle perfectly from the moment he first spawns, person B might have to wait days or even weeks to unlock the stuff which best serves her own needs, and every time they play each other in that time person A is going to have a huge advantage over person B, even if B is actually a much more skilled player who'll regularly win once she gets her own perfect loadout.
Provided that everyone gets access to equipment, perks and specialisations from the very start of their Spartan career, I'm all in favour of their inclusion: they give a few extra options on the battlefield and give players a better chance to have an impact on a game from spawn, whereas under classic systems how you perform often depends more on what gametype variant gets picked than actual player skill. I'm also not averse to players having to choose and complete a specialisation path before they can pick another: however, it would be nice to be able to find out exactly what a specialisation does before you pick it, and perhaps even be able to test it out in solo Spartan Ops games or whatever before you commit to it, rather than just having to rely on the incredibly vague in-game descriptions that Halo 4 provides.
In terms of the specialisations themselves, provided they're balanced, I don't mind what effects they have, although it would be interesting to see a system of trade-offs in terms of their effects rather than pure buffs. This would both give an advantage to purists who prefer to use weapon-only loadouts without perks, and also make customisation more tactical: perhaps you could take as many as you like, but each one lowers your maximum shields by 10%, meaning you gain versatility but lose durability. Another option would be that each perk gives you both a buff and a specific nerf: you can have a motion tracker which detects players even when standing still, but its range is halved; you can reload faster but carry less ammunition; you can increase the level of aim assist, but weapons fire slower, etc.
So, overall: a tentative, 'yes', provided that they're balanced and everyone has immediate, equal access to them. Otherwise, no thanks.