This might not interest you unless you are one of the big guys owning HTC Athena a.k.a HTC X7500, HTC Advantage, Dopod U1000 PocketPC devices. HTC will not help you keeping up-to-date with latest version of Windows Mobile releases from Microsoft. If you have the guts to loose warranty by tring cooked ROMs with new WM6.1 OS, AP4 from xda-dev is there.

I can say that this ROM was the most awaited ROM. Main reason is that the user-base of this device is not high due to the heavy price-tag of this device and it looks more of a UMPC rather than a WM PocketPC. Hence, less hackers, less ROM cookers. AP - Athena Project Team is the only team to release the custom cooked ROMs for this device and their previous ROM AP3 was quite a big-hit.
Using this AP4 ROM, my first impressions were not that great. The very fist thing I usually do right after flashing  ROM is to check the free memory left. Compared to other ROMs, this ROM had around 20 MB lesser! Just because this device is loaded with 128MB RAM, the 65MB is quite okay to play with unless you're a PRO memory hungry user in PocketPC.

Memory Issues:
Leave the memories aside, WM6.1 has some speed improvements which is hard to notice on normal usage but its true. Along with the updated Compact Framework 3.5, it's definitely fast enough.

Screenies:
No big customizations has been made in this ROM. Just the plain WM6.1 themes and skins. However this is a good practice as you can anytime customize the theme by yourself according to your likes.

I'm a RealVGA lover with 128 dpi and the Media Player problem is still not fixed but who cares when I rely on the free TcpMp which is far better than the default PocketPC Windows Media Player.

The Notification icons are not displayed properly in this 128dpi. This happens only in this ROM!

The HTC Home Today plug-in included in the ROM is huge and takes a lot of screen-estate. I never use it.

The new custom made dialer in Manilla interface looks amazing but never try using it. It is so poor in memory usage and hangs your device. Better stick to no phone skin mode at 128dpi.

SIP Keyboard issues:

TouchPal keyboard from teksoft is nice and inclded for free in this ROM too after the special permissions from the authors. The keyboard gives huge keys occupying the full width of the screen even in 128 dpi but it was damn slow and not friendly when the gestures to capitalize letters dont work. So I better stick to the default smaller stock keyboard SIP.

There is a very poor response with the keyboard and the suggesting options during SMS wont show up. This has to be fixed with small registry edit as bellow: