I've heard a number of things from various attys about DLA. I'll just pout off a number of things I heard... The main thing to know about the firm is that recently it has bought up a lot of firms to increase its share of the market. Some attys think that such a strategy may hurt the firm as a whole b/c they think that the firm may not have thought through/strategically made these moves. Another issue they had was that the firm doesnt seem to have an identity. The atmosphere will likely differ from one office to another at the firm too. It seems like mostly a bunch of different firms with one name presiding. Keep an eye on the revenue returns too, the profit-per-partner may have taken a hit from all this expansion.
PPP are over a mill I believe - they've gone up since the merger, not down, and they continue to rise each year. I think that at any huge firm, different offices will take on different personalities/atmospheres, as will any practice groups. The firm is growing, though, not just in terms of numbers, but in terms of client base, identity, prestige, etc. There are definitely drawbacks to working for any huge firm, but there are also benefits - easy to tranfer to different offices if you have to/want to move, great secondment opportunities, high profile clients, big impact with pro-bono projects.
If you have specific questions regarding the firm or specific offices, pm or email me - I can probably provide some good information to you as I have fairly strong ties to the firm.