I think Titanfall is fun. I like spending an hour now and then hunting Titans and killing pilots. However, the game is not the epic revolution everyone hoped for. Here are a few features the game should have in order to stand the test of time:
1) Much better costumization. The weapons are too few and not very inspiring. I would like something in style with BF4 or at least CoD. I would have loved to costumize my Titans' colours and emblems. It would be cool to be able to recognize a foe by his insigna. Today we are limited to three chassis. Way too little.
2) The maps should be a little more interesting. Today's maps feel repetitive.
3) The matches should last much longer. It should be practically possible for a team laging behind to recover. At the moment the matches are intensive but not epic.
4) I don't have a problem with the missing single player. I DO have a problem with a campaign which is so poor that it is tantamount to an insult to the players. It would have been better to not have a campaign at all in order to focus on customization and better maps.
5) A private lobby. Come on! The game is lacking features that are industry standards since many years.
Conclusion: Titanfall is a good (but overpriced) casual game. Something radical has to happen, however, if Respawn wants it to be a classic. They should put much effort in a massive (and free) patch.