How much better are the Classic 45 rpm vs 33 LPs?

I'm thinking about buying some of these. Some in print, some out. The out's are getting pricey. How much better do things sound in 45rpm vs 33.3? Thanks for your opinions!
expect some amazing dynamics, high signal/noise + low noise, shorter playing times of course. Higher cost is only worthwhile up to a certain point; don't break the bank. You know better than we what they're worth to you.
i own a bunch of them. many are great, not every one though, so i no longer buy them without hearing them first. they are way better then the classic 33 of the same title, but if you own early pressings or white label promos, some of those will be better at 33 then the newly minted 45's.

and beware those short playing times per side: 2 songs and yer on yer feet resleaving etc for the next side. at times that gets old fast... i would suggest trying a couple that appeal the most...
I think they are pretty damn good. I many of the titles in both 33 and 45 versions and in every case the 45 is noticeably better although the 33's are pretty good too. The way I see it if there is an album you really love, it's worth it to get the 45 version. But as Tagyerit points out, you need to keep in mind the shorter play time. In the case of the Tchaikovsky Violin Concerto they couldn't even squeeze the entire first movement onto one side so you have to change discs in the middle and that is really unfortunate.

I am not a universal endorser of all that Classic Records churns out, but I think they do a great job with many of their releases. Another excellent source (for classical only) is Cisco's Super Analogue Disc series which are consistently excellent although typically on available in 33 RPM. They do a very good job, but only reissue classical titles.
Some of the 45's are amazing--Reiner's Scheherezade, Kondrashin's Capriccio Italien and Espagnole, Reiner's Zarathustra, Gibson's Gounod etc. record, maybe the Reiner Respighi, although it's a bit bright, the Mercury Firebird, Chabrier, Prokofiev--others are a bit better than the 33's, but not much. You might be interested to know that the Speakers Corner website now announces a new series of Decca 45 reissues, starting with La Fille Mal Gardee in July. Don't run to the phone--neither Acoustic Sounds nor any of the other specialty dealers know anything about them yet.
thanks everyone !!
there are also singles 12"/33.5rpm that have wider grooves but different carts may act in that case differently and so is on different speeds.
i have lots of 12"/45rpm and most of the time they're all excellent.
speaking of 45's check out this link to a Steve Hoffman forum,

steve is cutting 25 classic jazz and blues lp's starting this winner. He is the best.