Slowdown, no Move controls, outdated textures. Half-baked attempt by Capcom to milk this cow again.
Sure it's great to have the game taking full advantage of a 50-inch flatscreen, but the HD transition kept the 2005 textures, making the graphics update marginal at best. On the PS2 in 2005, this game had the most top-notch graphics of its generation, on the HD update, they look below average. Actually, it may be even better to look at it in standard graphics than HD, as the blurriness and lack of definition gives it a little edge.
The control scheme, which was wonderful in 2005, feels a bit outdated in 2011. Not as horrendous and outdated as the first three Resident Evil games (practically unplayable by today's standards), but you can tell it hasn't aged so well. The button layout has been updated to match Resident Evil 5, which makes more sense. A huge head-scratcher is the lack of support for Move controls. Resident Evil 5 has it, The Wii version has motion control support, why this doesn't? This is another sign the game was rushed.
Something I found absolutely inexcusable is the horrible slowdown in some stages. And I mean the slowdown is bad. Very bad. You'd think at this point, they could have figured out to solve that!
What saves this game is the gameplay, action, and all the good stuff we remember this game for. If you've never played it, I can't recommend it more. Even with all the disadvantages it's still better than Resident Evil 5. With this game the PS3 becomes the first console you're able to play all the franchise's major releases.
The other reason to have it is if you don't own a PS2. If you do, forget this update and find a cheap PS2 copy. This update is a half-baked attempt by Capcom, and it deserves better.