So how well does it perform compare to other phones of today? Lets look at some benchmark (Quadrant) numbers:
* HTC G2(using MSM7230 at 800MHz) - 1499 * HTC Desire HD (using MSM8255 at 1GHz) - 1974
Now compare these with other phones using stock clock speeds (i.e. no over-clocking allowed here!):
* Droid X with Froyo (using TI OMAP3640 at 1GHz) - 1431 * HTC Incredible with Froyo (using QSD8650 at 1GHz) - 1202 * Samsung Galaxy S with 2.1 (using Hummingbird at 1GHz) - 880 (to be fair, you can apply XDA lag fix to bring this number up significantly, in this case - 2246)
(Source: http://smartphonebenchmarks.com)
As you can see, 800MHz MSM7230 is competitive with other 1GHz offerings. MSM8255 outperforms other 1GHz offerings by a significant margin except for Galaxy S (even though it is only using 2.1), which does feature a ultra-powerful GPU by today's standard (PowerVR SGX540). Could XDA developers find ways to increase 1974 past Galaxy S level? We will find out soon enough.
Updated (Oct 13, 2010): Here's the link to some benchmark numbers for Adreno 205 vs current champ - PowerVR SGX540 used in Samsung's Hummingbird.
Updated (Oct 25, 2010): It appears that MSM7230 is a very good overclocking processor! This is actually not very surprising. Original 1st generation processor found in Nexus One is known to overclock to around 1.2GHz without much hassle. With 45nm manufacturing instead of 65nm, it will overclock at least as well and likely better. As you can see in this table, G2 managed to hit 1.55GHz and produced Quadrant result of 2699 which is 2nd highest to date! I have every reason to believe that MSM8x55 will be able to overclock just as easily.