Dale said what was too lazy to get to. Betting patterns are very important to pay attention to especially with Laggy players. A tight player betting like that, I'd get out of the way since it would be a coinflip at best.

There could be some important clues in the strength of his raises.

When he was raising with mid-pairs had everyone limped in?
When he was calling down with A-high was it cheap relatively? (great advertiesment value)
When (and how much) does he raise preflop?
Will he raise any of the crap hands he showdowns or only quality ones?

Paying attention to these little bits of info become even more important when you are dealing with a Lagg.

- sed