You determine a race's ability adjustments by taking an average specimen and subtracting 10 from any even scores and 11 from any odd scores. So, having an odd number as an ability adjustments should be impossible. Since a creature can't have an ability score less than 1 (except temporarily, due to damage or drain), penalties greater than -10 should be impossible. Since any race with an average int below 3 isn't allowed for players, an int penalty greater than -8 should be impossible for a player race.
I'm going to consider the ability adjustments to be +10 str, +8 dex, +16 con, -8 int, -10 wis, -10 cha.
To compare this race to other races published by Wizards, lets look at half-ogre (Races of Destiny, p97) and Lolth-touched (Monster Manual IV, p92). Half-ogre is a base race that is large and gets +6 str, -2 dex, +2 con, -2 int, -2 cha for +2 LA. Lolth-touched is a template that gives +6 str, +6 con for +1 LA. That comes out to large size and +12 str, -2 dex, +8 con, -2 int, -2 cha for +3 LA.
So, relative to that, this race gets -2 str, +10 dex, +8 con, -6 int, -10 wis, -8 cha. I don't particularly object to giving a bonus to con for a penalty to a couple of mental ability scores. Con isn't a very problematic ability score.
I object to the substantial bonus to dex on a large creature on thematic grounds. I'd also be weary of allowing such a large penalty to wis. He's probably going to take classes with a poor will save. Unless he takes steadfast determination (Player's Handbook II, p83), he'll probably need to roll a 20 to make any will save.
Edit: Monster Manual has a table on page 296 that gives guidelines on ability score ranges for custom creatures. For a large creature, the strength adjustment should be between +8 and +16, the dexterity adjustment should be between -2 and +6, and the constitution adjustment should be between +0 and +12.