Pros: Supports 66MHz PCI. If your motherboard supports this then it does help. See "other thoughts" for test data.

Supports both 3.3v and 5v PCI slots. Will run at 33MHz or 66MHz depending what the motherboard supports.

An old article posted by Backblaze described their usage of this card in one generation of their cloud storage servers. This strongly suggests there shouldn't be anything terribly wrong with it.

Supports RAID, but I haven't used that feature so I can't say much about it. Also supports exposing the drives as single drives to the OS, and that's the method I have preferred.

Cons: None that I'm aware of.
This is an older card so it might be limited to 2TB max drive size. I haven't tried anything larger so I don't know.

Other Thoughts: Sil3124 chipset. Supports 3.3v and 5v, 33 and 66MHz 32-bit PCI slots. Desktop PC motherboards will normally be limited to 33MHz. PCI based server boards will usually have faster slots and then the 66MHz support comes into play.

I've seen some references to this card requiring PCI 2.3, but I tried it on some older P2 and P3 era motherboards that didn't meet this spec. I didn't find anything it wouldn't work with.

You can use this card to present single drives to the OS, you don't have to use it for RAID.

Supports both 3.3v and 5v operation. It is keyed for both and I have tested it working in both type of motherboards.
One of the boards I tested was an old Intel L440GX (slot-1 440GX), which has some 5V PCI slots which run at 66MHz. I'm pretty sure that scenario violates the PCI spec but Intel did it anyway. I confirmed through performance testing that this card will run 66MHz in 5V mode.

If your board supports it, 66MHz helps disk performance a lot, even with a single disk. A simple utility called 'Roadkil's diskspeed' under WinXP can show this. It reads a long piece of data, it's not skewed by the drive buffer.
In the test below, there was a single WD Red 2TB drive attached to the ADSA4R5, which was attached to an Intel L440GX motherboard, 2x P3-600/100, 1.5GB RAM. The only variable between these tests is the use of a 33 or 66MHz slot. These were the linear read results:
Blocksize 33MHz 66MHz
Cache 148.95MB/s 269.93MB/s
0.5KB 5.26MB/s 6.88MB/s
1KB 10.02MB/s 12.94MB/s
2KB 19.43MB/s 24.59MB/s
4KB 30.87MB/s 42.40MB/s
8KB 43.74MB/s 71.43MB/s
16KB 60.07MB/s 104.12MB/s
32KB 74.65MB/s 126.11MB/s
64KB 77.63MB/s 139.82MB/s
128KB 84.90MB/s 139.72MB/s
256KB 82.97MB/s 140.09MB/s
512KB 93.43MB/s 143.08MB/s
1024KB 94.10MB/s 141.34MB/s
This was with nothing else happening in the system, no network activity etc. 66MHz PCI is faster even with a single modern disk on a very old system (600MHz P3).
The limitation of that system was with GbE networking performance, but the disk controller by itself worked well.
The card was later moved to a Tyan S2882-D (AMD Opteron with multiple PCI-X buses) where it is working under CentOS.