The Scottish champions, who sealed their place in the group stages with a famous 3-0 win Shakhter Karagandy on Wednesday, were handed a group full of European heavyweights.
Barcelona, AC Milan and Ajax will provide the opposition for Lennon's side and, although he admits it will be tough, he does feel it represents some huge nights for the club.
"It is the best and the worst draw we could have got," Lennon told Sky Sports News.
"In terms of glamour I don't think it comes any better than Barcelona, Ajax and AC Milan but in terms of football it is probably the most difficult we could have got. I think there is a lot of excitement and the hard work was already done and we can really enjoy this tournament now.
"In terms of travelling, and the players obviously, it is not that bad and three wonderful footballing arenas.
"We get the chance to lock horns with Barcelona again and we are looking forward to three more great nights at least at Celtic Park and there is so much to savour about the draw.
"But from my point of view, and from a footballing point of view, it is going to be hugely difficult to even come through the first three phases of the group."
Lennon admits that he will be looking to add more players to his squad in the coming days before the transfer window closes and he says being in the group stages will help.
"It will in terms of even attracting players, due to the quality of player we are looking for," he continued.
"We lost three quality players in Gary [Hooper], Kelvin [Wilson] and Victor [Wanyama] and we haven't really replaced them - we have tried and the six seven weeks leading up to last night is always fraught, and we had to produce the team to come through and it just adds to the reputation of the team."
Lennon admits that Celtic were desperate to make the group stages, saying: "This means everything, the Scottish game is much maligned.
"We know the financial climate here, clubs are in trouble and people on the outside looking in think Celtic are going to win the league so you don't get much credit for that but for me personally and my development as a manager this means everything to me.
"Now it is all about football and can we take them on and work with more exciting players?"