Vespiquen is a great defensive Pokemon. It's got high defense stats, it's got it's signature moves Heal Order and Defend Order, as well as the very useful Attack Order.
It's Attack stats are very low, however. And, you also have to consider that it is Bug. Bug isn't a very good type in-game. It's never a good idea to add a Bug-type to a party.
And to add, the base power of the attacks it learn aren't very good. In fact, apart from Hyper Beam and Giga Impact as TMs, Attack Order is the strongest move it can possibly learn, unless you count Bug Buzz, which it can learn as a Combee.
So Vespiquen is a very defensive Pokemon in hindsight, but even then it's Bug-Flying type which causes a terrible type advantage.
All in all, I think I'm not the only one that can agree that Vespiquen is sort of useless in the game, not even serving as a proper HM slave - all it can learn is Cut. So yeah, pretty useless, I'd recommend not adding it to your team.
Hope I helped. :)