Do Jehovah's Witnesses believe in Jesus Christ? Yes, but they don't believe Jesus is God.
Their beliefs are far different than mainstream Christians. Consider the 141 Things Jehovah's Witnesses Can't Do. Did Jesus place all these restrictions upon Christians? Jesus did not give his followers a rigid set of rules and regulations. That's why critics say, they have 'run ahead' of Jesus. 2 John 1: 9 - 11
Jehovah's Witnesses say they are Christians. However they have knowingly added to the law of the Christ and judged fellow members harshly based on doctrines Jesus didn't teach. See disfellowshipping. As for judging, Jesus instructed his followers not to judge. Luke 6:35-37; Matthew 7:1. Jesus warned his followers against the leaven of the Pharisees which is hypocrisy, self righteousness, strict compliance with rules and regulations, judgment, and lack of God's love. Mark 8:15; Matthew 16:6,11,12; Luke 12:1;
JW's believe that Jesus is not the mediator between God and men like the Bible says in 1 Timothy 2:5 NIV. They believe Jesus is the mediator between God and the 144,000 ( 144000 ) anointed Christians. See Mediator This doctrine means that most Jehovah's Witnesses are not saved by Jesus unless they affiliate themselves with the anointed Jehovah's Witnesses and obey God's anointed slave. See What Does The Bible Say About The Faithful and Discreet Slave? Read more about anointed Jehovah's Witnesses vs JW's who belong to 'the Great Crowd'
The Watchtower also teaches Jehovah's Witnesses to hate people who leave their religion and those who disagree.  These are called 'apostates' and the Watchtower considers them to be 'the enemy'. Hatred is not Christian. Jesus taught us to love our enemies. (Luckily most Jehovah's Witnesses show compassion to everyone. However they are afraid to challenge Watchtower doctrines because they believe that would be rebellion against God.) 
Jehovah's Witnesses believe that Jesus was Jehovah's first born creation or his 'only-begotten Son'. God created all other things through Jesus.
To pay for the sins of man, Jesus served as a ransom sacrifice. They believe Jesus died on a torture 'stake', not a cross. Jehovah's Witnesses also believe that when the Bible refers to Archangel Michael, Apollyon (Abaddon), and the Word, this is symbolic language for Jesus.
1. The Watchtower has encouraged Jehovah's Witnesses to hate members who leave. Even though Jehovah's Witnesses are afraid to challenge the doctrines of the Watchtower, many of them reject the idea that they should hate anyone. See Apostate Jehovah's Witnesses