It was an enjoyable experience overall, but probably not sufficient to justify reading if it weren't for Alternative. Apart from the presentation (which is leagues ahead of any other VN I've read), there isn't much that Muv Luv is great at.

Characters are a mixed bag and the story (at least in Extra) doesn't really offer anything outside of setup for the sequel. While Extra may have been enjoyable, its more so in a guilty pleasure sort of way rather than anything with much substance. While Unlimited does introduce a more tangible story, it also suffers from the fact that it only really exists as setup to Alternative. It lacks the enjoyable qualities that made Extra worth getting through but lacks the payoff for any of its setup that made Alternative a good experience.

Ultimately, I don't regret playing through the Muv Luv series but I don't think it was a masterpiece. I think I can see why some people do see it that way, but there are just too many lows and not enough highs to justify such a position. Its probably still worth reading overall, but perhaps with tempered expectations.