Solid: well in that case just go and run with it. Because I'm bored, I'll give you a brief rundown of each Eeveelution, they're some of my favorites:
Vaporeon: awesome HP, great Special A, good Special D, bad everything else. They're hard to kill, even more so if you give them Acid Armor, Wish, Rest, or Aqua Ring. They're also capable on offense with Surf and Ice Beam. Maybe the most popular one.
Flareon: awesome Attack, great Special D, good Special A, bad everything else. Flareons aren't the greatest, because they can't use very many good attacks. If you give them Return, a good Fire attack, and some other offensive moves then Flareon can do some damage, but they're hindered by a bad moveset. They're also somewhat fragile.
Jolteon: Awesome Speed, great Special A, good Special D, bad everything else. These guys are really fast offensive pokemon. Give them a strong Electric special attack and at least one other special offense and they will do great damage and just about always attack first. You can also Baton Pass speed boosts to slow pokemon.
Umbreon: Awesome Special D, great defense, good HP, bad everything else. Umbreon is a pure wall. Very poor offense, your best means of dealing damage are attacks like Toxic and Payback. You can do all kinds of tricky stalling and defensive Umbreon tactics in competitive battling, but if you're just playing solo then Umbreon is hard to use.
Espeon: Awesome Special A, great Speed, good Special D, bad everything else. Espeon is like a slightly stronger, slightly slower Jolteon. Psychic attacks from Espeon are very powerful, and it can also boost itself up with Calm Mind. It's very good at passing around defensive abilities and can also learn a few good special attacks like Shadow Ball and Grass Knot.
Leafeon: Awesome Defense, great Attack, good Speed, bad everything else. Leafeon is a good physical attacker and tank, especially if you give him moves like Leaf Blade, Swords Dance, X-Scissor, or Return. Baton Passing around Swords Dance is awesome. Even though I admit it isn't as good as Espeon or Vaporeon, it's maybe my favorite of all the Eeveelutions.
Glaceon: Awesome Special A, great Defense, good Special D, bad everything else. Glaceon can be an okay tank if you boost up his HP, but otherwise functions best as a special attacker or a member of a team that likes to set up Hail. Its moveset isn't very good, but Glaceon has maybe the most powerful Ice Beam and Blizzard attacks in the game.