My DPS built sci officer comes top of the damage charts 9 out of 10 times totally slapping most tac officers. Not to mention the awesome career kills. -80% damage res for 30 seconds or add 15 seconds onto all cooldowns of a target anyone?
I went sci KDF; am loving it. You lack a dedicated ship until T5, which means you don't get all the target subs, or the console slots, or the bonus to detecting cloak or the boost to your aux and shield power levels. Still, that sensor scan and SNB are sexy, plus you can even fit cannons if you don't plan on going Vo'Quv. There isn't a real abundance of Sci Klinks, so you fill a much needed niche and make friends fast.
On an overall note, you have the largest ship in the game waiting for you at the end of the road.
I will echo all the other posters. I am a Klingon Science Officer, currently Cmdr3, and I'm enjoying it. Subnucleonic Beam is just so great, many people still have no clue what it is. Sensor scan rules, and if you go ground, there's some great things you can do with the right kits.
I fly in a BoP, and I do just fine damage-wise, and I heal too.